Energy Decomposition Analysis Coupled with Natural Orbitals for Chemical Valence and Nucleus-Independent Chemical Shift Analysis of Bonding, Stability, and Aromaticity of Functionalized Fulvenes: A Bonding Insight

This article references 31 other publications.

1. 1

   (a) Lewis, G. N. The Atom and the Molecule. J. Am. Chem. Soc. 1916, 38, 762,  DOI: 10.1021/ja02261a002

   1a

   The atom and the molecule

   Lewis, G. N.

   Journal of the American Chemical Society (1916), 38 (), 762-85CODEN: JACSAT; ISSN:0002-7863.

   cf. C. A. 71 3865 and Bray and Branch, C. A. 7, 3865. Compds. should be classed as polar and nonpolar rather than inorg. and org. These classes are roughly the same. A nonpolar mol. is one in which the electrons belonging to the individual atom are held by such restraints that they do not move far from their normal positions, while in the polar mols. the electrons, being more mobile, so move as to sep. the mol. into positive and negative parts. In an extremely polar mol. such as NaCl it is probable that in the great majority of the mols. the Cl atom has acquired a unit negative charge and therefore the Na atom a unit positive charge, and the process of ionization probably consists only in a further sepn. of these charged parts. If a weakly polar mol. comes into the neighborhood of a more polar one it becomes itself more polar. In this process the weaker bipole stretches and its moment increases. A "cubical atom" is proposed as a basis of a new theory of atomic structure. Thus Li is a cube with a single electron on one corner, Be has 2 electrons, B 3, C 4, N 5, O 6, and F 7. This view is in harmony with the theory developed by Parson, C. A. 10, 406. An atom is considered as having an unalterable kernel which possesses an excess of positive charges corresponding in number to the ordinal number of the group in the periodic table to which the element belongs (cf. Thomson, C. A. 8, 824). There is a shell of electrons around the kernel which, in the case of a neutral atom, contains negative electrons equal in number to the excess of positive charges of the kernel, but the number of electrons in the shell may vary during chem. changes between zero and 8. The atom tends to hold an even number of electrons in the shell (especially 8 at the corners of the cube) but the electrons may ordinarily pass from one position to another in this shell. Two atomic shells are mutually interpenetrable. The paper is a discussion of these ideas applied to the structure of atoms and compds.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaC28XlvFSl&md5=9f8b4fdf6c255a1c60dafaad766c9d3a

   (b) Shaik, S. Chem. – Eur. J. 2007, 28, 51

   There is no corresponding record for this reference.

   (c) Güsten, R.; Wiesemeyer, H.; Neufeld, D.; Menten, K. M.; Graf, U. U.; Jacobs, K.; Klein, B.; Ricken, O.; Risacher, C.; Stutzki, J. Astrophysical detection of the helium hydride ion HeH⁺. Nature 2019, 568, 357,  DOI: 10.1038/s41586-019-1090-x

   1c

   Astrophysical detection of the helium hydride ion HeH+

   Guesten, Rolf; Wiesemeyer, Helmut; Neufeld, David; Menten, Karl M.; Graf, Urs U.; Jacobs, Karl; Klein, Bernd; Ricken, Oliver; Risacher, Christophe; Stutzki, Juergen

   Nature (London, United Kingdom) (2019), 568 (7752), 357-359CODEN: NATUAS; ISSN:0028-0836. (Nature Research)

   During the dawn of chem., when the temp. of the young Universe had fallen below some 4,000 K, the ions of the light elements produced in Big Bang nucleosynthesis recombined in reverse order of their ionization potential. With their higher ionization potentials, the helium ions He2+ and He+ were the first to combine with free electrons, forming the first neutral atoms; the recombination of hydrogen followed. In this metal-free and low-d. environment, neutral helium atoms formed the Universe's first mol. bond in the helium hydride ion HeH+ through radiative assocn. with protons. As recombination progressed, the destruction of HeH+ created a path to the formation of mol. hydrogen. Despite its unquestioned importance in the evolution of the early Universe, the HeH+ ion has so far eluded unequivocal detection in interstellar space. In the lab. the ion was discovered3 as long ago as 1925, but only in the late 1970s was the possibility that HeH+ might exist in local astrophys. plasmas discussed. In particular, the conditions in planetary nebulae were shown to be suitable for producing potentially detectable column densities of HeH+. Here we report observations, based on advances in terahertz spectroscopy and a high-altitude observatory, of the rotational ground-state transition of HeH+ at a wavelength of 149.1 μm in the planetary nebula NGC 7027. This confirmation of the existence of HeH+ in nearby interstellar space constrains our understanding of the chem. networks that control the formation of this mol. ion, in particular the rates of radiative assocn. and dissociative recombination.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXovFaqs7c%253D&md5=a0247abe941666b1e388db07c0855284

   (d) https://www.scientificamerican.com/article/the-first-molecule-in-the-universe/.

   There is no corresponding record for this reference.

   (e) McCarthy, M. C.; Lee, K. L. K.; Loomis, R. A.; Burkhardt, A. M.; Shingledecker, C. N.; Charnley, S. B.; Cordiner, M. A.; Herbst, E.; Kalenskii, S.; Willis, E. R.; Xue, C.; Remijan, A. J.; McGuire, B. A. Interstellar detection of the highly polar five-membered ring cyanocyclopentadiene. Nat. Astron. 2021, 5, 176,  DOI: 10.1038/s41550-020-01213-y

   There is no corresponding record for this reference.
2. 2

   (a) Evans, W. J. Tutorial on the Role of Cyclopentadienyl Ligands in the Discovery of Molecular Complexes of the Rare-Earth and Actinide Metals in New Oxidation States. Organometallics 2016, 35, 3088,  DOI: 10.1021/acs.organomet.6b00466

   2a

   Tutorial on the Role of Cyclopentadienyl Ligands in the Discovery of Molecular Complexes of the Rare-Earth and Actinide Metals in New Oxidation States

   Evans, William J.

   Organometallics (2016), 35 (18), 3088-3100CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)

   A review. This tutorial is based on the award address for the 2015 American Chem. Society Award in Organometallic Chem. sponsored by the Dow Chem. Company, Midland, Michigan. A fundamental aspect of any element is the range of oxidn. states accessible for useful chem. This tutorial describes the recent expansion of the no. of oxidn. states available to the rare earth and actinide metals in mol. complexes that has resulted through organometallic chem. involving the cyclopentadienyl ligand. These discoveries demonstrate that the cyclopentadienyl ligand, which has been a key component in the development of organometallic chem. since the seminal discovery of ferrocene in the 1950s, continues to contribute to the advancement of science. Background information on the rare earth and actinide elements is presented as well as the sequence of events that led to these unexpected developments in the oxidn. state chem. of these metals.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhsFSjurnN&md5=afd9bc63ec9b7bc8cfb0707fde50d036

   (b) Mas-Roselló, J.; Herraiz, A. G.; Audic, B.; Laverny, A.; Cramer, N. Chiral Cyclopentadienyl Ligands: Design, Syntheses, and Applications in Asymmetric Catalysis. Angew. Chem., Int. Ed. 2020, 59, 2,  DOI: 10.1002/ange.202008166

   There is no corresponding record for this reference.

   (c) Fritz-Langhals, E. Silicon(II) Cation Cp*Si:⁺ X^–: A New Class of Efficient Catalysts in Organosilicon Chemistry. Org. Process Res. Dev. 2019, 23, 2369,  DOI: 10.1021/acs.oprd.9b00260

   2c

   Silicon(II) Cation Cp*Si:+ X-: A New Class of Efficient Catalysts in Organosilicon Chemistry

   Fritz-Langhals, Elke

   Organic Process Research & Development (2019), 23 (11), 2369-2377CODEN: OPRDFK; ISSN:1083-6160. (American Chemical Society)

   The catalytic activity of the pentamethylcyclopentadienylsilicon(II) cation Cp*Si:+ was investigated. It was shown that Cp*Si:+ efficiently catalyzes reactions of tech. relevance in organosilicon chem.: Cp*Si:+ proved to be a very efficient nonmetallic catalyst for the hydrosilylation of olefins at low catalyst amts. of <0.01 mol % and for the Piers-Rubinsztajn reaction in order to make controlled silicone topologies. The thermal induction of hydrosilylation which is important for the manufg. of silicone rubber can be achieved by small amts. of alkoxysilanes.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhvFChs77O&md5=2f7bfa906a93f7d90e4eb4522ad68ea1
3. 3

   (a) Trifonova, E. A.; Ankudinov, N. M.; Mikhaylov, A. A.; Chusov, D. A.; Nelyubina, Y. V.; Perekalin, D. S. A Planar-Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones. Angew. Chem., Int. Ed. 2018, 57, 7714,  DOI: 10.1002/anie.201801703

   3a

   A Planar-Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones

   Trifonova, Evgeniya A.; Ankudinov, Nikita M.; Mikhaylov, Andrey A.; Chusov, Denis A.; Nelyubina, Yulia V.; Perekalin, Dmitry S.

   Angewandte Chemie, International Edition (2018), 57 (26), 7714-7718CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

   The rapid development of enantioselective C-H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar-chiral rhodium catalyst [(C5H2tBu2CH2tBu)RhI2]2 in two steps from com. available [(cod)RhCl]2 and tert-butylacetylene. Pure enantiomers of the catalyst were obtained through sepn. of its diastereomeric adducts with natural (S)-proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones, e.g., I, in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee).

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXnslSmtbc%253D&md5=03028be8a5c98ffaa77aadcc613a21ad

   (b) Chena, W.-W.; Xu, M. -H. Recent advances in rhodium-catalyzed asymmetric synthesis of heterocycles. Org. Biomol. Chem. 2017, 15, 1029,  DOI: 10.1039/C6OB02021F

   There is no corresponding record for this reference.
4. 4

   Gould, C. A.; McClain, K. R.; Yu, J. M.; Groshens, T. J.; Furche, F.; Harvey, B. G.; Long, J. R. Synthesis and Magnetism of Neutral, Linear Metallocene Complexes of Terbium(II) and Dysprosium(II). J. Am. Chem. Soc. 2019, 141, 12967,  DOI: 10.1021/jacs.9b05816

   4

   Synthesis and Magnetism of Neutral, Linear Metallocene Complexes of Terbium(II) and Dysprosium(II)

   Gould, Colin A.; McClain, K. Randall; Yu, Jason M.; Groshens, Thomas J.; Furche, Filipp; Harvey, Benjamin G.; Long, Jeffrey R.

   Journal of the American Chemical Society (2019), 141 (33), 12967-12973CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)

   The divalent metallocene complexes Ln(CpiPr5)2 (Ln = Tb, Dy) were synthesized through the KC8 redn. of Ln(CpiPr5)2I intermediates and represent the first examples of neutral, linear metallocenes for these elements. X-ray diffraction anal., d. functional theory calcns., and magnetic susceptibility measurements indicate a 4fn5d1 electron configuration with strong s/d mixing that supports the linear coordination geometry. A comparison of the magnetic relaxation behavior of the two divalent metallocenes relative to salts of their trivalent counterparts, [Ln(CpiPr5)2][B(C6F5)4], reveals that lanthanide redn. has opposing effects for dysprosium and terbium, with magnetic relaxation times increasing from TbIII to TbII and decreasing from DyIII to DyII. The impact of this effect is most notably evident for Tb(CpiPr5)2, which displays an effective thermal barrier to magnetic relaxation of 1205 cm-1 and a 100-s blocking temp. of 52 K, the highest values yet obsd. for any nondysprosium single-mol. magnet.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhsFSku7jM&md5=133a22f38b1a0789ceb618e82209d538
5. 5

   (a) Arumugam, S.; Reddy, P. G.; Francis, M.; Kulkarni, A.; Roy, S.; Mondal, K. C. Highly fluorescent aryl-cyclopentadienyl ligands and their tetra-nuclear mixed metallic potassium–dysprosium clusters. RSC Adv. 2020, 10, 39366,  DOI: 10.1039/D0RA05316C

   5a

   Highly fluorescent aryl-cyclopentadienyl ligands and their tetra-nuclear mixed metallic potassium-dysprosium clusters

   Arumugam, Selvakumar; Reddy, Pulikanti Guruprasad; Francis, Maria; Kulkarni, Aditya; Roy, Sudipta; Mondal, Kartik Chandra

   RSC Advances (2020), 10 (65), 39366-39372CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)

   Two alkyl substituted triaryl-cyclopentadienyl ligands [4,4'-(4-phenylcyclopenta-1,3-diene-1,2-diyl)bis(methylbenzene) (1) and 4,4',4''-(cyclopenta-1,3-diene-1,2,4-triyl)tris(methylbenzene) (2)] have been synthesized via cross-aldol condensation followed by Zn-dust mediated cyclization and acid catalyzed dehydration reactions. The fluorescence properties of 1 and 2 have been studied in soln. and solid state. The ligands exhibited aggregation-induced emission enhancement (AIEE) in THF/water soln. 1 and 2 have been found to be significantly more fluorescent in the solid state than in their resp. solns. This phenomenon can be attributed to the strong intermol. CH···π interactions present in 1 and 2 which leads to the tight packing of mols. in their solid-state. Both 1, 2 and their corresponding anions have been studied by theor. calcns. Ligands 1 and 2 have been shown to react with anhyd. DyCl3 in the presence of potassium metal at high temp. to afford two fluorescent chloride-bridged tetra-nuclear mixed potassium-dysprosium metallocenes [(Me2Cp)4Dy2IIICl4K2]·3.5(C7H8) (5) and [(Me3Cp)4Dy2IIICl4K2]·3(C7H8) (6), resp. in good yields.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXit1aksLfN&md5=9da2e07c0dbf23648263f13100c3d740

   (b) Roitershtein, D. M.; Puntus, L. N.; Vinogradov, A. A.; Lyssenko, K. A.; Minyaev, M. E.; Dobrokhodov, M. D.; Taidakov, I. V.; Varaksina, E. A.; Churakov, A. V.; Nifantév, I. E. Polyphenylcyclopentadienyl Ligands as an Effective Light-Harvesting π-Bonded Antenna for Lanthanide⁺³ Ions. Inorg. Chem. 2018, 57, 10199,  DOI: 10.1021/acs.inorgchem.8b01405

   5b

   Polyphenylcyclopentadienyl Ligands as an Effective Light-Harvesting π-Bonded Antenna for Lanthanide +3 Ions

   Roitershtein, Dmitrii M.; Puntus, Lada N.; Vinogradov, Alexander A.; Lyssenko, Konstantin A.; Minyaev, Mikhail E.; Dobrokhodov, Mikhail D.; Taidakov, Ilya V.; Varaksina, Evgenia A.; Churakov, Andrei V.; Nifantev, Ilya E.

   Inorganic Chemistry (2018), 57 (16), 10199-10213CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)

   A new approach to design antenna-ligands to enhance the photoluminescence of lanthanide coordination compds. was developed based on a π-type ligand - the polyphenyl-substituted cyclopentadienyl. The complexes of di-, tri-, and tetra-Ph cyclopentadienyl ligands with Tb and Gd were synthesized and all the possible structural types from mononuclear to di- and tetranuclear complexes, as well as a coordination polymers were obtained. All types of the complexes were studied by single-crystal x-ray diffraction and optical spectroscopy. All Tb complexes are luminescent at ambient temp. and two of them have relatively high quantum yields (50 and 60%). Anal. of energy transfer process was performed and supported by quantum chem. calcns. The role of a low-lying intraligand charge transfer state formed by extra coordination with K+ in the Tb3+ ion luminescence sensitization is discussed. New aspects for design of lanthanide complexes contg. π-type ligands with desired luminescence properties are proposed.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtlyqsbrM&md5=17de1076d771d7e228591cfa44ed5b6f

   (c) Yang, L.; Ye, J.; Xu, L.; Yang, X.; Gong, W.; Lin, Y.; Ning, G. Synthesis and properties of aggregation-induced emission enhancement compounds derived from triarylcyclopentadiene. RSC Adv. 2012, 2, 11529,  DOI: 10.1039/c2ra21622a

   5c

   Synthesis and properties of aggregation-induced emission enhancement compounds derived from triarylcyclopentadiene

   Yang, Lijian; Ye, Junwei; Xu, Lifeng; Yang, Xinyu; Gong, Weitao; Lin, Yuan; Ning, Guiling

   RSC Advances (2012), 2 (30), 11529-11535CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)

   Several triarylcyclopentadiene derivs. were synthesized and their crystal structures and photoluminescence properties in soln. and aggregation state were studied. Their max. fluorescence emission wavelengths were 452-483 nm. Four of them have weak emission in soln. but intense emission when aggregated in water/acetonitrile mixt. or in crystals showing a typical aggregation-induced emission enhancement (AIEE). The crystal structure anal. reveals that the arom. C-H···π interactions are the origin of the AIEE. Addnl., DFT calcns., and the thermal and electrochem. properties of these compds. were investigated. The synthesis of the target compds. was achieved by an aldol condensation or Suzuki coupling of appropriate reactants. The title compds. thus formed included 1-(3,4-diphenyl-1,3-cyclopentadien-1-yl)naphthalene (I) and related substances.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsF2rsLzF&md5=5cc3a64eddbd5ec36e221a0e3db8dc62
6. 6

   (a) Wu, J.; Demeshko, S.; Decherta, S.; Meyer, F. Hexanuclear [Cp*Dy]₆ single-molecule magnet. Chem. Commun. 2020, 56, 3887,  DOI: 10.1039/C9CC09774K

   6a

   Hexanuclear [Cp*Dy]6 single-molecule magnet

   Wu, Jianfeng; Demeshko, Serhiy; Dechert, Sebastian; Meyer, Franc

   Chemical Communications (Cambridge, United Kingdom) (2020), 56 (27), 3887-3890CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)

   A hexanuclear cluster [(Cp*Dy)6K4Cl16(THF)6], [Cp*Dy]6, was constructed from six {Cp*DyIII} synthons in which the strongly coordinating Cp*- caps det. the local anisotropy axes. Structural characterization of [Cp*Dy]6 shows two almost parallel triangular (Cp*Dy)3 fragments that are linked by the K+ and Cl- ions. Magnetic measurements reveal slow thermal relaxation and fast quantum tunneling relaxation in the absence of an external d.c. field. After applying a weak d.c. field, the quantum tunneling relaxation is efficiently suppressed, giving a sizable energy barrier of 561 K, which represents the current record energy barrier for high nuclearity organometallic SMMs.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXktVKnsL8%253D&md5=7be4db2c1e18e4701e1efb02e66832cf

   (b) Guo, F.-S.; Day, B. M.; Chen, Y.-C.; Tong, M.-L.; Ki, A. M.; Layfield, R. A. A Dysprosium Metallocene Single-Molecule Magnet Functioning at the Axial Limit. Angew. Chem., Int. Ed. 2017, 56, 11445,  DOI: 10.1002/anie.201705426

   6b

   A Dysprosium Metallocene Single-Molecule Magnet Functioning at the Axial Limit

   Guo, Fu-Sheng; Day, Benjamin M.; Chen, Yan-Cong; Tong, Ming-Liang; Mansikkamaeki, Akseli; Layfield, Richard A.

   Angewandte Chemie, International Edition (2017), 56 (38), 11445-11449CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

   Abstraction of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] (1Dy Cpttt=1,2,4-tri(tert-butyl)cyclopentadienide) by the triethylsilylium cation produces the first base-free rare-earth metallocenium cation [(Cpttt)2Dy]+ (2Dy) as a salt of the non-coordinating [B(C6F5)4]- anion. Magnetic measurements reveal that [2Dy][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm-1 (1837 K) in zero field and a record magnetic blocking temp. of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low-lying Kramers doublets correspond to a well-defined MJ value, with no significant mixing even in the higher doublets.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFOmu7vO&md5=9f842e7ade2c47dfd324dd6301fe0900

   (c) Guo, F.-S.; Day, B. M.; Chen, Y. C.; Tong, M.-L.; Mansikkamaki, A.; Layfield, R. A. Magnetic hysteresis up to 80 kelvin in a dysprosium metallocene single-molecule magnet. Science 2018, 362, 1400,  DOI: 10.1126/science.aav0652

   6c

   Magnetic hysteresis up to 80 kelvin in a dysprosium metallocene single-molecule magnet

   Guo, Fu-Sheng; Day, Benjamin M.; Chen, Yan-Cong; Tong, Ming-Liang; Mansikkamaeki, Akseli; Layfield, Richard A.

   Science (Washington, DC, United States) (2018), 362 (6421), 1400-1403CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)

   Single-mol. magnets (SMMs) contg. only one metal center may represent the lower size limit for mol.-based magnetic information storage materials. Their current drawback is that all SMMs require liq.-helium cooling to show magnetic memory effects. We now report a chem. strategy to access the dysprosium metallocene cation [(CpiPr5)Dy(Cp*)]+ (CpiPr5, penta-iso-propylcyclopentadienyl; Cp*, pentamethylcyclopentadienyl), which displays magnetic hysteresis above liq.-nitrogen temps. An effective energy barrier to reversal of the magnetization of Ueff = 1541 wave no. is also measured. The magnetic blocking temp. of TB = 80 K for this cation overcomes an essential barrier toward the development of nanomagnet devices that function at practical temps.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisFeksL3F&md5=13d4c594df879bd5b507078447ab9af2

   (d) Goodwin, C. A. P.; Ortu, F.; Reta, D.; Chilton, N. F.; Mills, D. P. Molecular magnetic hysteresis at 60 kelvin in dysprosocenium. Nature 2017, 548, 439,  DOI: 10.1038/nature23447

   6d

   Molecular magnetic hysteresis at 60 kelvin in dysprosocenium

   Goodwin, Conrad A. P.; Ortu, Fabrizio; Reta, Daniel; Chilton, Nicholas F.; Mills, David P.

   Nature (London, United Kingdom) (2017), 548 (7668), 439-442CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)

   Lanthanides were studied extensively for potential applications in quantum information processing and high-d. data storage at the mol. and at. scale. Exptl. achievements include reading and manipulating single nuclear spins, exploiting at. clock transitions for robust qubits and, most recently, magnetic data storage in single atoms. Single-mol. magnets exhibit magnetic hysteresis of mol. origin-a magnetic memory effect and a prerequisite of data storage-and so far lanthanide examples have exhibited this phenomenon at the highest temps. However, in the nearly 25 years since the discovery of single-mol. magnets, hysteresis temps. have increased from 4 K to only ∼14 K using a consistent magnetic field sweep rate of ∼20 Oe per s, although higher temps. were achieved by using very fast sweep rates (for example, 30 K with 200 Oe per s). Here the authors report a hexa-tert-butyldysprosocenium complex-[Dy(Cpttt)2][B(C6F5)4], with Cpttt = {C5H2tBu3-1,2,4} and tBu = CMe3-which exhibits magnetic hysteresis at temps. of up to 60 K at a sweep rate of 22 Oe per s. The authors observe a clear change in the relaxation dynamics at this temp., which persists in magnetically dild. samples, suggesting that the origin of the hysteresis is the localized metal-ligand vibrational modes that are unique to dysprosocenium. Ab initio calcns. of spin dynamics demonstrate that magnetic relaxation at high temps. is due to local mol. vibrations. With judicious mol. design, magnetic data storage in single mols. at temps. above liq. nitrogen should be possible.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtlyisbfF&md5=8bc379889e7ac64db1802a4e14fed96e

   (e) Moreno, L. E.; Baldovı, J. J.; Arino, A. G.; Coronado, E. Exploring the High-Temperature Frontier in Molecular Nanomagnets: From Lanthanides to Actinides. Inorg. Chem. 2019, 58, 11883,  DOI: 10.1021/acs.inorgchem.9b01610

   There is no corresponding record for this reference.

   (f) Meihaus, K. R.; Fieser, M. E.; Corbey, J. F.; Evans, W. J.; Long, J. R. Record High Single-Ion Magnetic Moments Through 4fⁿ5d¹ Electron Configurations in the Divalent Lanthanide Complexes [(C₅H₄SiMe₃)₃Ln]⁻. J. Am. Chem. Soc. 2015, 137, 9855,  DOI: 10.1021/jacs.5b03710

   6f

   Record High Single-Ion Magnetic Moments Through 4fn5d1 Electron Configurations in the Divalent Lanthanide Complexes [(C5H4SiMe3)3Ln]-

   Meihaus, Katie R.; Fieser, Megan E.; Corbey, Jordan F.; Evans, William J.; Long, Jeffrey R.

   Journal of the American Chemical Society (2015), 137 (31), 9855-9860CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)

   The recently reported series of divalent lanthanide complex salts, [K(2.2.2-cryptand)][Cp'3Ln] (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm; Cp' = C5H4SiMe3) and the analogous trivalent complexes, Cp'3Ln, were characterized via d.c. and a.c. magnetic susceptibility measurements. The salts of [Cp'3Dy]- and [Cp'3Ho]- exhibit magnetic moments of 11.3 and 11.4 μB, resp., which are the highest moments reported to date for any monometallic mol. species. The magnetic moments measured at room temp. support the assignments of a 4fn+1 configuration for Ln = Sm, Eu, Tm and a 4fn5d1 configuration for Ln = Y, La, Gd, Tb, Dy, Ho, Er. In the cases of Ln = Ce, Pr, Nd, simple models do not accurately predict the exptl. room temp. magnetic moments. Although an LS coupling scheme is a useful starting point, it is not sufficient to describe the complex magnetic behavior and electronic structure of these intriguing mols. While no slow magnetic relaxation was obsd. for any member of the series under zero applied d.c. field, the large moments accessible with such mixed configurations present important case studies in the pursuit of magnetic materials with inherently larger magnetic moments. This is essential for the design of new bulk magnetic materials and for diminishing processes such as quantum tunneling of the magnetization in single-mol. magnets.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFKhtrrO&md5=aae9141ea1f18288016eec4460c6ecd3

   (g) Demir, S.; Zadrozny, J. M.; Nippe, M.; Long, J. R. Exchange Coupling and Magnetic Blocking in Bipyrimidyl Radical-Bridged Dilanthanide Complexes. J. Am. Chem. Soc. 2012, 134, 18546,  DOI: 10.1021/ja308945d

   6g

   Exchange coupling and magnetic blocking in bipyrimidyl radical-bridged dilanthanide complexes

   Demir, Selvan; Zadrozny, Joseph M.; Nippe, Michael; Long, Jeffrey R.

   Journal of the American Chemical Society (2012), 134 (45), 18546-18549CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)

   The synthesis and magnetic properties of three new bipyrimidyl radical-bridged dilanthanide complexes, [(Cp*2Ln)2(μ-bpym•)]+ (Ln = Gd, Tb, Dy; bpym = 2,2'-bipyrimidine), are reported. Strong LnIII-bpym•- exchange coupling is obsd. for all species, as indicated by the increases in χMT at low temps. For the GdIII-contg. complex, a fit to the data reveals antiferromagnetic coupling with J = -10 cm-1 to give an S = 13/2 ground state. The TbIII and DyIII congeners show single-mol. magnet behavior with relaxation barriers of Ueff = 44(2) and 87.8(3) cm-1, resp., a consequence of the large magnetic anisotropies imparted by these ions. Significantly, the latter complex exhibits a divergence of the field-cooled and zero-field-cooled dc susceptibility data at 6.5 K and magnetic hysteresis below this temp.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsF2kt7fE&md5=b81a4903834e742619a8d3d7619ab091
7. 7

   Demir, S.; Zadrozny, J. M.; Long, J. R. Large Spin-Relaxation Barriers for the Low-Symmetry Organolanthanide Complexes [Cp*₂Ln(BPh₄)] (Cp*=pentamethylcyclopentadienyl; Ln=Tb, Dy). Chem. – Eur. J. 2014, 20, 9524,  DOI: 10.1002/chem.201403751

   7

   Large Spin-Relaxation Barriers for the Low-Symmetry Organolanthanide Complexes [Cp*2Ln(BPh4)] (Cp*=pentamethylcyclopentadienyl; Ln=Tb, Dy)

   Demir, Selvan; Zadrozny, Joseph M.; Long, Jeffrey R.

   Chemistry - A European Journal (2014), 20 (31), 9524-9529CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)

   Single-mol. magnets comprising one spin center represent a fundamental size limit for spin-based information storage. Such an application hinges upon the realization of mols. possessing substantial barriers to spin inversion. Axially sym. complexes of lanthanides hold the most promise for this due to their inherently high magnetic anisotropies and low tunneling probabilities. Herein, we demonstrate that strikingly large spin reversal barriers of 216 and 331 cm-1 can also be realized in low-symmetry lanthanide tetraphenylborate complexes of the type [Cp*2Ln(BPh4)] (Cp*=pentamethylcyclopentadienyl; Ln=Tb (1) and Dy (2)). The dysprosium congener showed hysteretic magnetization data up to 5.3 K. Further studies of the magnetic relaxation processes of 1 and 2 under applied dc fields and upon diln. within a matrix of [Cp*2Y(BPh4)] revealed considerable suppression of the tunneling pathway, emphasizing the strong influence of dipolar interactions on the low-temp. magnetization dynamics in these systems.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtVGqtbjL&md5=89fb583d54fe5371174ab63fee935729
8. 8

   (a) Ramirez, F.; Levy, S. Communications - Triphenylphosphonium-cyclopentadienylide. J. Org. Chem. 1956, 21, 488,  DOI: 10.1021/jo01110a614

   8a

   Triphenylphosphoniumcyclopentadienylide

   Ramirez, Fausto; Levy, Stephen

   Journal of Organic Chemistry (1956), 21 (), 488-9CODEN: JOCEAH; ISSN:0022-3263.

   Bromination of cyclopentadiene in CH2Cl2 and addn. of 2 mole equivs. Ph3P, then of 2 mole equivs. aq. NaOH give triphenylphosphoniumcyclopentadienylide (I), pale yellow crystals from PhMe, m. 229-31°. I is not affected by hot dil. aq. or alc. KOH, does not react with cyclohexanone even at elevated temps., does not absorb H in C6H6 soln. in the presence of PtO2, and is very stable in a solid state and in soln. In dil. HBr I absorbs 2 mole equivs. H in the presence of Pt catalyst, yielding triphenylcyclopentylphosphonium bromide (II), m. 261-3°. The principal ultraviolet absorption bands of I and II and the main infrared absorption bands of I are given.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaG2sXitFGrug%253D%253D&md5=fc8d5886731890f14e7e509522dbc7ad

   (b) Mueller-Westerhoff, U. Metallocenes from fulvenes: A new synthesis of functionally substituted ferrocenes. Tetrahedron Lett. 1972, 13, 4639,  DOI: 10.1016/S0040-4039(01)94386-2

   There is no corresponding record for this reference.

   (c) Kunz, D.; Johnsen, E. Ø.; Monsler, B.; Rominger, F. Highly Ylidic Imidazoline-Based Fulvenes as Suitable Precursors for the Synthesis of Imidazolium-Substituted Metallocenes. Chem. – Eur. J. 2008, 14, 10909,  DOI: 10.1002/chem.200801956

   8c

   Highly ylidic imidazoline-based fulvenes as suitable precursors for the synthesis of imidazolium-substituted metallocenes

   Kunz, Doris; Johnsen, Erik Oe; Monsler, Birgit; Rominger, Frank

   Chemistry - A European Journal (2008), 14 (35), 10909-10914CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)

   Imidazoline-derived fulvenes prepd. from CpLi and an ethoxytetramethylimidazolium tetrafluoroborate show the highest known ylidic character for 6,6-diaminofulvenes. This is displayed in the extraordinary long exocyclic double bond of 1.430 Å. Therefore these fulvenes exhibit cyclopentadienyl anion-like reactivity, namely, protonation to cyclopentadienes and reaction with Fe(II) chloride to give Cp-substituted 2-imidazolium ferrocenes and with [Cp*Ru(MeCN)3]OTf to give ruthenocene complex.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXpsFeg&md5=a5506d0d3a9c13329d26cc21111a578c

   (d) Schmid, D.; Seyboldt, A.; Kunz, D. A Direct Synthesis of a Strongly Zwitterionic 6,6’-Diaminofulvalene. Z. Naturforsch. B 2014, 69, 580,  DOI: 10.5560/znb.2014-4015

   8d

   A direct synthesis of a strongly zwitterionic 6,6'-diaminofulvalene

   Schmid, Dominic; Seyboldt, Alexander; Kunz, Doris

   Zeitschrift fuer Naturforschung, B: A Journal of Chemical Sciences (2014), 69 (5), 580-588CODEN: ZNBSEN; ISSN:0932-0776. (Verlag der Zeitschrift fuer Naturforschung)

   Reaction of the dipyrido-annulated guanidinium salt I (R = NMe2, X = Cl) with 1 equiv cyclopentadienylsodium afforded the dipyrido-annulated diaminofulvalene II in one step with 33% isolated yield. This shortens the initial route that applies a known fulvalene synthesis via uronium salt I (R = OEt, X = BF4) by two steps and avoids the need for a sacrificial equiv. of cyclopentadienylsodium. Although x-ray structure anal. [orthorhombic, space group P212121, a 10.4017(3), b 13.2552(3), c 17.3514(4) Å, V 2392.35(10) Å3, Z 4] reveals a shorter exocyclic double bond than obsd. in the corresponding diaminofulvene, DFT calcns. show a stronger zwitterionic character for II.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtFWhtr3K&md5=4610097645711067d27ed5fd09c209ae

   (e) Brownie, J.; Baird, M. Coordination complexes of aryl- and alkylphosphonium cyclopentadienylides (cyclopentadienylidene ylides), C₅R₄PR′R″R‴ (R = H, alkyl, aryl; R′, R′′, R′′′ = alkyl, aryl). Coord. Chem. Rev. 2008, 252, 1734,  DOI: 10.1016/j.ccr.2007.12.028

   8e

   Coordination complexes of aryl- and alkylphosphonium cyclopentadienylides (cyclopentadienylidene ylides), C5R4PR'R''R''' (R = H, alkyl, aryl; R', R'', R''' = alkyl, aryl)

   Brownie, John H.; Baird, Michael C.

   Coordination Chemistry Reviews (2008), 252 (15-17), 1734-1754CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)

   A review. The coordination chem. of phosphonium cyclopentadienylides C5R4PRR'R''R''' (R = H, alkyl, aryl; R', R'', R''' = alkyl, aryl) is reviewed critically. In part, perhaps, because of difficulties in characterizing many of the coordination complexes obtained in the early days, research on this class of potentially very interesting ligands stagnated and virtually no publications dealing with their coordination chem. have appeared in over two decades. As a result, the reactivities of most of these compds. remain largely unexplored and the effects of ligand substitution on metal complex structures and reactivities were very little examd. Although significant contributions on this subject were made, much interesting chem. remains to be examd. and discovered using this class of ligand. If the wt. of modern spectroscopic techniques is brought to bear on the some of the structural questions that have appeared in the literature, new insights may be garnered. This review does not deal with analogous groups 15 and 16 ylides which are reported, such as those of S, As and Sb. Although these ylides are related to the P ylides, it is beyond the scope of this review to discuss their coordination chem.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXntlSks78%253D&md5=ca0f1fce5af2a71d0dc3e1adefc9383f

   (g) Lin, R.; Zhang, H.; Li, S.; Wang, J.; Xia, H. New Highly Stable Metallabenzenes via Nucleophilic Aromatic Substitution Reaction. Chem. – Eur. J. 2011, 17, 4223,  DOI: 10.1002/chem.201003566

   8g

   New highly stable metallabenzenes via nucleophilic aromatic substitution reaction

   Lin, Ran; Zhang, Hong; Li, Shunhua; Wang, Jiani; Xia, Haiping

   Chemistry - A European Journal (2011), 17 (15), 4223-4231CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)

   Treatment of the ruthenabenzene [Ru{CHC(PPh3)CHC(PPh3)CH}Cl2(PPh3)2]Cl (1) with excess 8-hydroxyquinoline in the presence of AcONa under air atm. produced the SNAr product I (3, R1 = R2 = +PPh3, X = Cl, n = 2). Ruthenabenzene 3 could be stable in the soln. of weak alkali or weak acid. However, reaction of 3 with NaOH afforded a 7:1 mixt. of regioisomeric mono-phosphonium-substituted ruthenabenzenes (4, 5; shown as I; 4, R1 = +PPh3, R2 = H, X = Cl, n = 1; 5, R1 = H, R2 = +PPh3, X = Cl, n = 1), presumably involving a P-C bond cleavage of the metallacycle. Complex 3 was also reactive to HCl, which results in a transformation of 3 to ruthenabenzene [Ru{CHC(PPh3)CHC(PPh3)C}Cl2(C9H6NO)(PPh3)]Cl (6) in high yield. Thermal stability tests showed that ruthenabenzenes 4, 5, and 6 have remarkable thermal stability both in solid state and in soln. under air atm. Ruthenabenzenes 4 and 5 were found to be fluorescent in common solvents and have spectral behaviors comparable to those org. multicyclic compds. contg. large π-extended systems.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXjvVShsLs%253D&md5=2d8fe22ca812c7180ab25a000d70a6d6

   (h) Xu, C.; Wang, Z.-Q.; Li, Z.; Wang, W.-Z.; Hao, A.-Q.; Fu, W.-J.; Gong, J.-F.; Ji, B.-M.; Song, M.-P. 1,3-Diphosphorus Ylide Cyclopentadienylium Salts: Synthesis, Structures, and Application in Coupling Reactions. Organometallics 2012, 31, 798,  DOI: 10.1021/om201267q

   8h

   1,3-Diphosphorus Ylide Cyclopentadienylium Salts: Synthesis, Structures, and Application in Coupling Reactions

   Xu, Chen; Wang, Zhi-Qiang; Li, Zhen; Wang, Wei-Zhou; Hao, Xin-Qi; Fu, Wei-Jun; Gong, Jun-Fang; Ji, Bao-Ming; Song, Mao-Ping

   Organometallics (2012), 31 (3), 798-801CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)

   The 1,3-diphosphorus ylide cyclopentadienylium salts (C5H3)(PPh3)2I (1) and (C5H3)[P(4-CH3-Ph)3]2I (2) have been prepd. from the reaction of 1,1'-dichloromercurioferrocene with Pd(PPh3)4 and with Pd[P(4-CH3-Ph)3]4, resp. The mol. structure of 1 has been detd. by x-ray diffraction analyses. The Pd(OAc)2/1 or 2/KtOBu system is highly efficient for the coupling reactions of aryl chlorides at room temp.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtVymsbw%253D&md5=abc16b2c3b929ef58ac7c07e503373d4

   (i) Schmid, D.; Seyboldt, A.; Kunz, D. Reaction of Iron-and Tungsten Carbonyls with a Zwitterionic Fulvalene. Z. anorg. allg. Chem. 2015, 641, 2228,  DOI: 10.1002/zaac.201500564

   8i

   Reaction of Iron- and Tungsten Carbonyls with a Zwitterionic Fulvalene

   Schmid, Dominic; Seyboldt, Alexander; Kunz, Doris

   Zeitschrift fuer Anorganische und Allgemeine Chemie (2015), 641 (12-13), 2228-2232CODEN: ZAACAB; ISSN:1521-3749. (Wiley-VCH Verlag GmbH & Co. KGaA)

   The highly dipolar fulvalene 1 reacts with pentacarbonyl iron(0) and hexacarbonyl tungsten(0) complexes under irradn. with UV light. The cyclopentadienyl complexes 2 and 3 formed are analyzed by NMR and IR spectroscopy as well as x-ray anal. They are the first zwitterionic carbonyl complexes of fulvenes or fulvalenes. In the case of iron, the dinuclear complex 2 consisting of a dicarbonyliron(+I)-tetracarbonylferrat(-I) moiety is formed, whereas in the case of tungsten, the mononuclear tricarbonyl tungsten(0) complex 3 is obtained.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsVOmsbnK&md5=1c6ebe47c11805de0f8acce259cb77c6

   (j) Schmid, D.; Seyboldt, A.; Eichele, K.; Kunz, D. Chiral amino-phosphine and amido-phosphine complexes of Ir and Mg. Catalytic applications in olefin hydroamination. Dalton Trans. 2016, 45, 12028,  DOI: 10.1039/C6DT01146B

   8j

   Chiral amino-phosphine and amido-phosphine complexes of Ir and Mg. Catalytic applications in olefin hydroamination

   Schmid, Bernhard; Friess, Sibylle; Herrera, Alberto; Linden, Anthony; Heinemann, Frank W.; Locke, Harald; Harder, Sjoerd; Dorta, Romano

   Dalton Transactions (2016), 45 (30), 12028-12040CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)

   The reactions of rac- and (S,S)-trans-9,10-dihydro-9,10-ethanoanthracene-11,12-diamine (ANDEN) with PClPh2 in the presence of NEt3 yield the chiral amino-phosphine ligands rac-6 and (S,S)-6, resp., on multi-gram scales. Both forms of 6 react quant. with MgPh2 to afford the C2-sym., N-bound magnesium amidophosphine complexes rac-7 and (S,S)-7. The former crystallizes as a racemic conglomerate, which is a rare occurrence. Mixing (S,S)- or rac-6 with [IrCl(COE)2]2 leads in both cases to the homochiral dinuclear chloro-bridged P-ligated aminophosphine Ir complexes (S,S,S,S)-9 and rac-9 in excellent yields. X-ray quality single crystals only grow as the racemic compd. (or 'true racemate') rac-9 thanks to its lowered soly. In the coordinating solvent MeCN, rac-9 transforms in high yield into mononuclear Ir-complex rac-10. The crystal structures of compds. rac-6, (S,S)-7, rac-9, and rac-10 reveal the ambidentate nature of the P-N function: amide-coordination in the Mg-complex (S,S)-7 and P-chelation of the softer Ir(I) centers in complexes rac-9 and rac-10. Also, the crystal structures show flexible, symmetry lowering seven-membered P-chelate rings in the Ir complexes and a surprising amt. of deformation within the ANDEN backbone. The simulation of this deformation by DFT and SCF calcns. indicates low energy barriers. (S,S)-7 and (S,S,S,S)-9 catalyze the intra- and intermol. hydroamination of alkenes, resp.: 5 mol% of (S,S)-7 affords 2-methyl-4,4'-diphenylcyclopentylamine quant. (7% ee), and 2.5 mol% of (S,S,S,S)-9 in the presence of 5.0 mol% co-catalyst (LDA, PhLi, or MgPh2) gives exo-(2-arylamino)bornanes in up to 68% yield and up to 16% ee.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtFCiurrN&md5=9039eb3d11e41a2756f18d03f0139142

   (k) Mazzotta, F.; Zitzer, G.; Speiser, B.; Kunz, D. Electron-Deficient Imidazolium Substituted Cp Ligands and their Ru Complexes. Chem. – Eur. J. 2020, 26, 16291,  DOI: 10.1002/chem.202002801

   8k

   Electron-Deficient Imidazolium Substituted Cp Ligands and their Ru Complexes

   Mazzotta, Fabio; Zitzer, Georg; Speiser, Bernd; Kunz, Doris

   Chemistry - A European Journal (2020), 26 (69), 16291-16305CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)

   The synthesis of electron-poor mono-, di- and tri(imidazolium)-substituted Cp-ylides is presented and their electronic properties are discussed based on NMR spectroscopy, X-ray structure analyses, electrochem. investigations and DFT calcns. as well as by their reactivity toward [Ru(CH3CN)3Cp*](PF6). With mono- and di(imidazolium)-substituted cyclopentadienides the resp. monocationic and dicationic ruthenocenes are formed (X-ray), whereas tri(imidazolium) cyclopentadienides are too electron-poor to form the ruthenocenes. Cyclic voltammetric anal. of the ruthenocenes shows reversible oxidn. at a potential that increases with every addnl. electron-withdrawing imidazolium substituent at the Cp ligand by 0.53-0.55 V in an electrolyte based on a weakly coordinating anion. A reversible oxidn. can be obsd. for the free 1,3-disubstituted ligand as well.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvFKjtLnE&md5=6a530e3d2f9e9d3ba406743403b4d619
9. 9

   (a) Zhao, L.; Pan, S.; Holzmann, N.; Schwerdtfeger, P.; Frenking, G. Chemical Bonding and Bonding Models of Main-Group Compounds. Chem. Rev. 2019, 119, 8781,  DOI: 10.1021/acs.chemrev.8b00722

   9a

   Chemical Bonding and Bonding Models of Main-Group Compounds

   Zhao, Lili; Pan, Sudip; Holzmann, Nicole; Schwerdtfeger, Peter; Frenking, Gernot

   Chemical Reviews (Washington, DC, United States) (2019), 119 (14), 8781-8845CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)

   The focus of this review is the presentation of the most important aspects of chem. bonding in mols. of the main group atoms according to the current state of knowledge. Special attention is given to the difference between the phys. mechanism of covalent bond formation and its description with chem. bonding models, which are often confused. This is partly due to historical reasons, since until the development of quantum theory there was no phys. basis for understanding the chem. bond. In the absence of such a basis, chemists developed heuristic models that proved extremely valuable for understanding and predicting exptl. studies. The great success of these simple models and the assocd. rules led to the fact that the model conceptions were regarded as real images of phys. reality. The complicated world of quantum theory, which eludes human imagination, made it difficult to link heuristic models of chem. bonding with quantum chem. knowledge. In the early days of quantum chem., some suggestions were made which have since proved untenable. In recent decades, there has been a stormy development of quantum chem. methods, which are not limited to the quant. accuracy of the calcd. properties. Also, methods have been developed where the exptl. developed models can be quant. expressed and visually represented using math. well-defined terms that are derived from quantum chem. calcns. The calcd. nos. may however not be measurable values. Nevertheless, as orientation data for the interpretation and classification of exptl. findings as well as a guideline for new expts., they form a coordinate system that defines the multidimensional world of chem., which corresponds to the Hilbert space formalism of physics. The nonmeasurability of model values is not a weakness of chem. but a characteristic by which the infinite complexity of the material world becomes scientifically accessible and very useful for chem. research. This review examines the basis of the commonly used quantum chem. methods for calcg. mols. and for analyzing their electronic structure. The bonding situation in selected representative mols. of main-group atoms is discussed. The results are compared with textbook knowledge of common chem.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXht1Kns77L&md5=e16ab87a0cd1735cb0a873109607f138

   (b) Zhao, L.; Hermann, M.; Schwarz, W. H. E.; Frenking, G. The Lewis electron-pair bonding model: modern energy decomposition analysis. Nat. Rev. Chem. 2019, 3, 48,  DOI: 10.1038/s41570-018-0060-4

   9b

   The Lewis electron-pair bonding model: modern energy decomposition analysis

   Zhao, Lili; Hermann, Markus; Schwarz, W. H. Eugen; Frenking, Gernot

   Nature Reviews Chemistry (2019), 3 (1), 48-63CODEN: NRCAF7; ISSN:2397-3358. (Nature Research)

   A review. Breaking down the calcd. interaction energy between two or more fragments into well-defined terms enables a phys. meaningful understanding of chem. bonding. Energy decompn. anal. (EDA) is a powerful method that connects the results of accurate quantum chem. calcns. with the Lewis electron-pair bonding model. The combination of EDA with natural orbitals for chem. valence (NOCV) links the heuristic Lewis picture with quant. MO theory complemented by Pauli repulsion and Coulombic interactions. The EDA-NOCV method affords results that provide a phys. sound picture of chem. bonding between any atoms. We present and discuss results for the prototypical main-group diatomics H2, N2, CO and BF, before comparing bonding in N2 and C2H2 with that in heavier homologues. The discussion on multiply bonded species is continued with a description of B2 and its N-heterocyclic carbene adducts.

   >> More from SciFinder ^®

   https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXnsFCmurk%253D&md5=7fcf5f6eb257e5f975912ff58e93bdd2

   (c) Zhao, L.; von Hopffgarten, M.; Andrada, D. M.; Frenking, G. Energy Decomposition Analysis. WIREs Comput. Mol. Sci. 2018, 8, e1345

   There is no corresponding record for this reference.
10. 10

    (a) Ramirez, F.; Desai, N. B.; Hansen, B.; McKelvie, N. HEXAPHENYLCARBODIPHOSPHORANE, (C₆H₅)₃PCP(C₆H₅)₃. J. Am. Chem. Soc. 1961, 83, 3539,  DOI: 10.1021/ja01477a052

    10a

    Hexaphenylcarbodiphosphorane, (C6H5)3P:C:P(C6H5)3

    Ramirez, Fausto; Desai, N. B.; Hansen, B.; McKelvie, N.

    Journal of the American Chemical Society (1961), 83 (), 3539-40CODEN: JACSAT; ISSN:0002-7863.

    cf. CA 52, 4532d. --A new type of P compd., R3P:C:PR3, a carbodiphosphorane, was prepd. Thus, 12.4 g. (Ph3PCH:PPh3)Br (I) added to 1.0 g. K in 100 ml. boiling diglyme [225 ml. (STP) gas evolved after 20 min.] and the soln. faltered and cooled yielded 6.4 g. title compd. (II), m. 208-10°, infrared (I.R.) strong band 7.6 μ, shoulder 7.8 μ (Nujol mull), absorbed in the 275-379 mμ region, λ 325 mμ (ε 0.7 × 104), 258 mμ (ε 0.6 × 104), 225 (ε 3 × 104) (all in cyclohexane), 325 mμ band disappeared if the soln. came in contact with moisture, did not exhibit electron-spin resonance absorption, insensitive to dry O, H2O-sol. Titration of a soln. of II with 0.1N HCl showed the presence of a diacidic base. Aq. solns. were fairly stable, but eventually crystals deposited. When II was treated with H2O and quickly filtered it produced a 6% yield of H2O-insol. Ph3P:CHP(O)Ph2, m. 157-8° (C6H6-hexane), strong doulbet 8.50 and 8.56 μ and strong shoulder 8.3 μ (in CH2Cl2). Addn. of 0.1N HBr to the filtrate pptd. 80% of the original I. When cryst. II was exposed (20 hrs.) to a wet N stream, nearly complete conversion to III took place (with C6H6 as the by-product). The addn. of 1 mole equiv. Br to II in CH2Cl2 produced a 70% yield of (Ph3P:CBrPPh3)Br (IV), m. 278-9°, bands at 9.40 and 11.7 μ (Nujol mull). The addn. of Br to I in CHCl3 also produced IV. Ph3P and CH2Br2, 2:1 mole ratio, were heated to 150° to give (Ph3PCH2PPh3)Br2 (V), 20% yield, m. 308-10° (EtOH), bands at 12.05 and 12.23 μ (Nujol mull). A 1:5 mole ratio at 60° for 18 hrs. produced 20% V and 40% (BrCH2PPh3)Br, m. 240-1°, bands at 12.13 and 12.70 μ (Nujol mull). Treatment of V with aq. Na2CO3 produced I, m. 270-1°, bands at 8.15 and 12.40 μ (Nujol mull).

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF38Xks1Wjsg%253D%253D&md5=8cc6b7af15c83519d3a17c342c8f969a

    (b) Tonner, R.; Frenking, G. C(NHC)₂: Divalent Carbon(0) Compounds with N-Heterocyclic Carbene Ligands—Theoretical Evidence for a Class of Molecules with Promising Chemical Properties. Angew. Chem., Int. Ed. 2007, 46, 8695,  DOI: 10.1002/anie.200701632

    10b

    C(NHC)2: divalent carbon(0) compounds with N-heterocyclic carbene ligands-theoretical evidence for a class of molecules with promising chemical properties

    Tonner, Ralf; Frenking, Gernot

    Angewandte Chemie, International Edition (2007), 46 (45), 8695-8698CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Quantum-chem. calcns. predict that the exptl. still unknown carbodicarbenes C(NHC)2 are a synthetically accessible class of divalent carbon(0) compds. which are very strong nucleophiles and bases that may be useful ligands for transition-metal complexes.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtl2rs77J&md5=b8ddf74395791a98a4ac8d4b93f97786

    (c) Dyker, C. A.; Lavallo, V.; Donnadieu, B.; Bertrand, G. Synthesis of an Extremely Bent Acyclic Allene (A “Carbodicarbene”): A Strong Donor Ligand. Angew. Chem., Int. Ed. 2008, 47, 3206,  DOI: 10.1002/anie.200705620

    10c

    Synthesis of an extremely bent acyclic allene (A "carbodicarbene"): a strong donor ligand

    Dyker, C. Adam; Lavallo, Vincent; Donnadieu, Bruno; Bertrand, Guy

    Angewandte Chemie, International Edition (2008), 47 (17), 3206-3209CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Pushed to the limit: Pushing C=Cπ bonds to the breaking point by using a push-push substitution pattern forces allenes to bend (see structure; C light blue, N dark blue). An acyclic allene featuring a C=C=C bond angle of 134.8° has been isolated in which the typically sp-hybridized central carbon atom approaches a configuration that has two lone pairs of electrons, and acts as a very strong η1-donor ligand for transition metals.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXlvVCrsrY%253D&md5=6fa04f9719bd47c20d7996f900fd6645

    (d) Fürstner, A.; Alcarazo, M.; Goddard, R.; Lehmann, C. W. Coordination Chemistry of Ene-1,1-diamines and a Prototype “Carbodicarbene”. Angew. Chem., Int. Ed. 2008, 47, 3210,  DOI: 10.1002/anie.200705798

    10d

    Coordination chemistry of ene-1,1-diamines and a prototype "carbodicarbene"

    Fuerstner, Alois; Alcarazo, Manuel; Goddard, Richard; Lehmann, Christian W.

    Angewandte Chemie, International Edition (2008), 47 (17), 3210-3214CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Carbophilic Lewis acids can polarize a coordinated π-bond by a slippage mechanism. Stable ylide or enolate Au complexes of ene-1,1-diamines not only emulate this property, but also reveal the exceptional donor capacity of such electron-rich olefin ligands. Also, the 1st metal complex of a tetraaminoallene, [[(Me2N)2C:C:C(NMe2)2][AuPPh3]]+[SbF6]- (19), prepd. in 72% yield from (Me2N)2C:C:C(NMe2)2, [AuCl(PPh3)] and NaSbF6 in THF, is reported, which features a prototype carbodicarbene ligand bound to a transition-metal template. The structures of 19 and of 6 other new compds. are reported by x-ray crystallog.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXlvVCrsrc%253D&md5=254cbd129abfbe0d6f81e600dbbea3bb

    (e) Tonner, R.; Öxler, F.; Neumüller, B.; Petz, W.; Frenking, G. Carbodiphosphoranes: The Chemistry of Divalent Carbon(0). Angew. Chem., Int. Ed. 2006, 45, 8038,  DOI: 10.1002/anie.200602552

    10e

    Carbodiphosphoranes: The chemistry of divalent carbon(0)

    Tonner, Ralf; Oexler, Florian; Neumueller, Bernhard; Petz, Wolfgang; Frenking, Gernot

    Angewandte Chemie, International Edition (2006), 45 (47), 8038-8042CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Optimized geometry, first and second protonation energies and complexation energies were calcd. for carbodiphosphoranes R3PCPR3, P-heterocyclic diphosphoranes cyclo-R22P(C)(CH:Q)PR22 and compared to the ref. value for N-heterocyclic carbenes and proton sponge; the results and NBO anal. indicate that the central carbon atom in the acyclic and cyclic carbodiphosphoranes may be best described as C(0), bearing its four electrons as two lone pairs and bound to phosphorus by P→C dative bonds. Silver complex of the protonated carbodiphosphorane, [[(PPh3)2CH]2Ag][BF4]2 (5) was prepd. and characterized by x-ray crystallog. The geometry and bond dissocn. energy was calcd. for digold complex [(PH3)2C(AuCl)2] (6) and compared with those for N-heterocyclic carbene complex [(ImC)(AuCl)2] (7, ImC = 1,3-dihydro-2H-imidazol-2-ylidene). The results for 6 and 7 prove the ability of carbodiphosphoranes to serve as four-electron donors and feature the presence of Au-Au aurophilic bond in 7 and the absence of aurophilic interactions in 6. The structural features of the carbodiphosphoranes give rise to unusual properties as confirmed by expt. The synthesis of a triply charged mols. in which two protonated carbodiphosphoranes serve as donor ligands to an Ag+ center supports the bonding model.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhtleksrnP&md5=5b1eaa4676fc510b49ebd6000573c892
11. 11

    Gorantla, S. M. N. V. T.; Pan, S.; Mondal, K. C.; Frenking, G. Stabilization of Linear C₃ by Two Donor Ligands: A Theoretical Study of L-C₃-L (L=PPh₃, NHC^Me, cAAC^Me). Chem. – Eur. J. 2020, 26, 14211,  DOI: 10.1002/chem.202003064

    11

    Stabilization of Linear C3 by Two Donor Ligands: A Theoretical Study of L-C3-L (L=PPh3, NHCMe, cAACMe)

    Gorantla, Sai Manoj N. V. T.; Pan, Sudip; Mondal, Kartik Chandra; Frenking, Gernot

    Chemistry - A European Journal (2020), 26 (62), 14211-14220CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Quantum chem. studies using d. functional theory and ab initio methods have been carried out for the mols. L-C3-L with L=PPh3 (1), NHCMe (2, NHC=N-heterocyclic carbene), and cAACMe (3, cAAC=cyclic (alkyl)(amino) carbene). The calcns. predict that 1 and 2 have equil. geometries where the ligands are bonded with rather acute bonding angles at the linear C3 moiety. The phosphine adduct 1 has a synclinal (gauche) conformation whereas 2 exhibits a trans conformation of the ligands. In contrast, the compd. 3 possesses a nearly linear arrangement of the carbene ligands at the C3 fragment. The bond dissocn. energies of the ligands have the order 1<2<3. The bonding anal. using charge and energy decompn. methods suggests that 3 is best described as a cumulene with electron-sharing double bonds between neutral fragments (cAACMe)2 and C3 in the resp. electronic quintet state yielding (cAACMe)=C3=(cAACMe). In contrast, 1 and 2 possess electron-sharing and dative bonds between pos. charged ligands [(PPh3)2]+ or [(NHCMe)2]+ and neg. charged [C3]- fragments in the resp. doublet state.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvFKisrrO&md5=1aeae349f5ecad7c2a39145fbe63afc1
12. 12

    (a) Sidgwick, N. V. The Electronic Theory of Valency, Clarendon, Oxford, 1927.

    There is no corresponding record for this reference.

    (b) Himmel, D.; Krossing, I.; Schnepf, A. Dative Bonds in Main-Group Compounds: A Case for Fewer Arrows!. Angew. Chem., Int. Ed. 2014, 53, 370,  DOI: 10.1002/anie.201300461

    12b

    Dative Bonds in Main-Group Compounds: A Case for Fewer Arrows!

    Himmel, Daniel; Krossing, Ingo; Schnepf, Andreas

    Angewandte Chemie, International Edition (2014), 53 (2), 370-374CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    The use of dative bonds to describe the electronic structure of main-group compds. has come into vogue in recent years. But where are the limits When does the description as a dative bond make sense and when is this view misleading. This Essay develops the idea on the basis of current examples.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhslynsr7J&md5=6ec2829c4596a9b8df1abf4a34a3f210

    (c) Frenking, G. Dative Bonds in Main-Group Compounds: A Case for More Arrows!. Angew. Chem., Int. Ed. 2014, 53, 6040,  DOI: 10.1002/anie.201311022

    12c

    Dative Bonds in Main-Group Compounds: A Case for More Arrows!

    Frenking, Gernot

    Angewandte Chemie, International Edition (2014), 53 (24), 6040-6046CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    In their recently published essay, Himmel, Krossing, and Schnepf (HKS) criticized the use of arrows in structural formulas for mols. of main-group elements that has become popular in the last years. Herein, I take up the contraposition to the criticism of HKS and show that the description of a previously unrecognized class of main-group compds. as donor-acceptor complexes is not only in agreement with exptl. observations and with quantum mech. calcns., it has also proven to be a very useful model for classifying known compds., as well as for the prediction of new mols. with unusual bonds and reactivities.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXosV2htLY%253D&md5=de6834a606d97521bd7e81549ff09fce

    (d) Himmel, D.; Krossing, I.; Schnepf, A. Dative or Not Dative?. Angew. Chem., Int. Ed. 2014, 53, 6047,  DOI: 10.1002/anie.201403078

    12d

    Dative or Not Dative?

    Himmel, Daniel; Krossing, Ingo; Schnepf, Andreas

    Angewandte Chemie, International Edition (2014), 53 (24), 6047-6048CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    A discussion of the constitution and nomenclature of dative bonds.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXos1CjsLY%253D&md5=a7c43f17514b87e6fec78cccf6dd80ba
13. 13

    (a) Varshavskii, Y. S. Russ. J. Gen. Chem. 1980, 50, 406

    There is no corresponding record for this reference.

    (b) Varshavskii, Y. S. Attempt to Describe Some Reactions of Organic Molecules Containing the R₁C Group in Terms of Donor-Acceptor Interaction. Zh. Obshch. Khim. 1980, 50, 514

    13b

    Attempt to describe some reactions of organic molecules containing the R2C: group in donor-acceptor interaction terms

    Varshavskii, Yu. S.

    Zhurnal Obshchei Khimii (1980), 50 (3), 514-18CODEN: ZOKHA4; ISSN:0044-460X.

    Reactions involving diazomethane derivs. and ylides and metathesis reactions were discussed.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL3cXlsV2iurY%253D&md5=9d9a332ccc351d775b59014dbdf12e86
14. 14

    (a) Becke, A. D. Density-functional exchange-energy approximation with correct asymptotic behavior. Phys. Rev. A 1988, 38, 3098,  DOI: 10.1103/PhysRevA.38.3098

    14a

    Density-functional exchange-energy approximation with correct asymptotic behavior

    Becke, A. D.

    Physical Review A: Atomic, Molecular, and Optical Physics (1988), 38 (6), 3098-100CODEN: PLRAAN; ISSN:0556-2791.

    Current gradient-cor. d.-functional approxns. for the exchange energies of at. and mol. systems fail to reproduce the correct 1/r asymptotic behavior of the exchange-energy d. A gradient-cor. exchange-energy functional is given with the proper asymptotic limit. This functional, contg. only one parameter, fits the exact Hartree-Fock exchange energies of a wide variety of at. systems with remarkable accuracy, surpassing the performance of previous functionals contg. two parameters or more.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL1cXmtlOhsLo%253D&md5=d4d219c134a5a90f689a8abed04d82cc

    (b) Perdew, J. P. Density-functional approximation for the correlation energy of the inhomogeneous electron gas. Phys. Rev. B 1986, 33, 8822,  DOI: 10.1103/PhysRevB.33.8822

    14b

    Density-functional approximation for the correlation energy of the inhomogeneous electron gas

    Perdew

    Physical review. B, Condensed matter (1986), 33 (12), 8822-8824 ISSN:0163-1829.

    There is no expanded citation for this reference.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2sfgsFSktA%253D%253D&md5=fb343a074cf09acda3e96d7f13ec2c7e

    (c) Grimme, S.; Ehrlich, S.; Goerigk, L. Effect of the damping function in dispersion corrected density functional theory. J. Comput. Chem. 2011, 32, 1456,  DOI: 10.1002/jcc.21759

    14c

    Effect of the damping function in dispersion corrected density functional theory

    Grimme, Stefan; Ehrlich, Stephan; Goerigk, Lars

    Journal of Computational Chemistry (2011), 32 (7), 1456-1465CODEN: JCCHDD; ISSN:0192-8651. (John Wiley & Sons, Inc.)

    It is shown by an extensive benchmark on mol. energy data that the math. form of the damping function in DFT-D methods has only a minor impact on the quality of the results. For 12 different functionals, a std. "zero-damping" formula and rational damping to finite values for small interat. distances according to Becke and Johnson (BJ-damping) has been tested. The same (DFT-D3) scheme for the computation of the dispersion coeffs. is used. The BJ-damping requires one fit parameter more for each functional (three instead of two) but has the advantage of avoiding repulsive interat. forces at shorter distances. With BJ-damping better results for nonbonded distances and more clear effects of intramol. dispersion in four representative mol. structures are found. For the noncovalently-bonded structures in the S22 set, both schemes lead to very similar intermol. distances. For noncovalent interaction energies BJ-damping performs slightly better but both variants can be recommended in general. The exception to this is Hartree-Fock that can be recommended only in the BJ-variant and which is then close to the accuracy of cor. GGAs for non-covalent interactions. According to the thermodn. benchmarks BJ-damping is more accurate esp. for medium-range electron correlation problems and only small and practically insignificant double-counting effects are obsd. It seems to provide a phys. correct short-range behavior of correlation/dispersion even with unmodified std. functionals. In any case, the differences between the two methods are much smaller than the overall dispersion effect and often also smaller than the influence of the underlying d. functional. © 2011 Wiley Periodicals, Inc.; J. Comput. Chem., 2011.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXjsF2isL0%253D&md5=370c4fe3164f548718b4bfcf22d1c753

    (d) Grimme, S.; Antony, J.; Ehrlich, S.; Krieg, H. A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. J. Chem. Phys. 2010, 132, 154104,  DOI: 10.1063/1.3382344

    14d

    A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu

    Grimme, Stefan; Antony, Jens; Ehrlich, Stephan; Krieg, Helge

    Journal of Chemical Physics (2010), 132 (15), 154104/1-154104/19CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)

    The method of dispersion correction as an add-on to std. Kohn-Sham d. functional theory (DFT-D) has been refined regarding higher accuracy, broader range of applicability, and less empiricism. The main new ingredients are atom-pairwise specific dispersion coeffs. and cutoff radii that are both computed from first principles. The coeffs. for new eighth-order dispersion terms are computed using established recursion relations. System (geometry) dependent information is used for the first time in a DFT-D type approach by employing the new concept of fractional coordination nos. (CN). They are used to interpolate between dispersion coeffs. of atoms in different chem. environments. The method only requires adjustment of two global parameters for each d. functional, is asymptotically exact for a gas of weakly interacting neutral atoms, and easily allows the computation of at. forces. Three-body nonadditivity terms are considered. The method has been assessed on std. benchmark sets for inter- and intramol. noncovalent interactions with a particular emphasis on a consistent description of light and heavy element systems. The mean abs. deviations for the S22 benchmark set of noncovalent interactions for 11 std. d. functionals decrease by 15%-40% compared to the previous (already accurate) DFT-D version. Spectacular improvements are found for a tripeptide-folding model and all tested metallic systems. The rectification of the long-range behavior and the use of more accurate C6 coeffs. also lead to a much better description of large (infinite) systems as shown for graphene sheets and the adsorption of benzene on an Ag(111) surface. For graphene it is found that the inclusion of three-body terms substantially (by about 10%) weakens the interlayer binding. We propose the revised DFT-D method as a general tool for the computation of the dispersion energy in mols. and solids of any kind with DFT and related (low-cost) electronic structure methods for large systems. (c) 2010 American Institute of Physics.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXkvVyks7o%253D&md5=2bca89d904579d5565537a0820dc2ae8

    (e) Weigend, F.; Ahlrichs, R. Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy. Phys. Chem. Chem. Phys. 2005, 7, 3297,  DOI: 10.1039/b508541a

    14e

    Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy

    Weigend, Florian; Ahlrichs, Reinhart

    Physical Chemistry Chemical Physics (2005), 7 (18), 3297-3305CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)

    Gaussian basis sets of quadruple zeta valence quality for Rb-Rn are presented, as well as bases of split valence and triple zeta valence quality for H-Rn. The latter were obtained by (partly) modifying bases developed previously. A large set of more than 300 mols. representing (nearly) all elements-except lanthanides-in their common oxidn. states was used to assess the quality of the bases all across the periodic table. Quantities investigated were atomization energies, dipole moments and structure parameters for Hartree-Fock, d. functional theory and correlated methods, for which we had chosen Moller-Plesset perturbation theory as an example. Finally recommendations are given which type of basis set is used best for a certain level of theory and a desired quality of results.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXpsFWgu7o%253D&md5=a820fb6055c993b50c405ba0fc62b194

    (f) Weigend, F. Accurate Coulomb-fitting basis sets for H to Rn. Phys. Chem. Chem. Phys. 2006, 8, 1057,  DOI: 10.1039/b515623h

    14f

    Accurate Coulomb-fitting basis sets for H to Rn

    Weigend, Florian

    Physical Chemistry Chemical Physics (2006), 8 (9), 1057-1065CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)

    A series of auxiliary basis sets to fit Coulomb potentials for the elements H to Rn (except lanthanides) is presented. For each element only one auxiliary basis set is needed to approx. Coulomb energies in conjunction with orbital basis sets of split valence, triple zeta valence and quadruple zeta valence quality with errors of typically below ca. 0.15 kJ mol-1 per atom; this was demonstrated in conjunction with the recently developed orbital basis sets of types def2-SV(P), def2-TZVP and def2-QZVPP for a large set of small mols. representing (nearly) each element in all of its common oxidn. states. These auxiliary bases are slightly more than three times larger than orbital bases of split valence quality. Compared to non-approximated treatments, computation times for the Coulomb part are reduced by a factor of ca. 8 for def2-SV(P) orbital bases, ca. 25 for def2-TZVP and ca. 100 for def2-QZVPP orbital bases.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xhs12ntrc%253D&md5=314690393f1e21096541a317a80e563c
15. 15

    Gaussian 16, Revision A.03, Frisch, M. J., Gaussian, Inc., Wallingford CT. 2016.

    There is no corresponding record for this reference.
16. 16

    (a) Weinhold, F.; Landis, C. Valency and Bonding, A Natural Bond Orbital Donor – Acceptor Perspective, Cambridge University Press, Cambridge, 2005.

    There is no corresponding record for this reference.

    (b) Landis, C. R.; Weinhold, F. The NBO View of Chemical Bonding, in, G., Frenking, S., Shaik (eds.), The Chemical Bond: Fundamental Aspects of Chemical Bonding. Wiley, 2014, pp. 91– 120.

    There is no corresponding record for this reference.

    (c) Bickelhaupt, F. M.; Baerends, E. J. Kohn-Sham Density Functional Theory: Predicting and Understanding Chemistry. In Rev. Comput. Chem.; Lipkowitz, K. B., Boyd, D. B., Eds.; Wiley-VCH: New York, 2000; Vol. 15, pp. 1– 86.

    There is no corresponding record for this reference.
17. 17

    Wiberg, K. B. Application of the pople-santry-segal CNDO method to the cyclopropylcarbinyl and cyclobutyl cation and to bicyclobutane. Tetrahedron 1968, 24, 1083,  DOI: 10.1016/0040-4020(68)88057-3

    17

    Application of the Pople-Santry-Segal complete neglect of differential overlap method to the cyclopropyl-carbinyl and cyclobutyl cation and to bicyclobutane

    Wiberg, Kenneth B.

    Tetrahedron (1968), 24 (3), 1083-96CODEN: TETRAB; ISSN:0040-4020.

    The CNDO method was applied to the cyclopropylcarbinyl and cyclobutyl cations, and gave results which are in very good accord with exptl. data. A cross-ring interaction is calcd. to be of importance with cyclobutyl derivs., and agrees with the large difference in rate observed with equatorial and axial leaving groups. Some properties of bicyclobutane as well as the relative energies for some models of the activated complex for the thermal rearrangement of bicyclobutane were also calcd. and compared with exptl. data. The CNDO method appears to have considerable promise in the investigation of org. chem. phenomena. 31 references.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF1cXlvV2qsQ%253D%253D&md5=528e518bff09ca52cafe664462adc09d
18. 18

    Glendening, E. D.; Landis, C. R.; Weinhold, F. NBO 6.0: Natural bond orbital analysis program. J. Comput. Chem. 2013, 34, 1429,  DOI: 10.1002/jcc.23266

    18

    NBO 6.0: Natural bond orbital analysis program

    Glendening, Eric D.; Landis, Clark R.; Weinhold, Frank

    Journal of Computational Chemistry (2013), 34 (16), 1429-1437CODEN: JCCHDD; ISSN:0192-8651. (John Wiley & Sons, Inc.)

    We describe principal features of the newly released version, NBO 6.0, of the natural bond orbital anal. program, that provides novel "link-free" interactivity with host electronic structure systems, improved search algorithms and labeling conventions for a broader range of chem. species, and new anal. options that significantly extend the range of chem. applications. We sketch the motivation and implementation of program changes and describe newer anal. options with illustrative applications. © 2013 Wiley Periodicals, Inc.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjvVegurc%253D&md5=fb48d2b4c2eb40b7754268b53882ccc9
19. 19

    Ziegler, T.; Rauk, A. On the calculation of bonding energies by the Hartree Fock Slater method. Theor. Chim. Acta 1977, 46, 1,  DOI: 10.1007/BF02401406

    19

    On the calculation of bonding energies by the Hartree Fock Slater method. I. The transition state method

    Ziegler, Tom; Rauk, Arvi

    Theoretica Chimica Acta (1977), 46 (1), 1-10CODEN: TCHAAM; ISSN:0040-5744.

    A transition-state method is given for calg. bonding energies and bond distances within the Hartree-Fock-Slater method. Calcns. on a no. of diat. mols. and a few transition metal complexes show better agreement with expt. than corresponding Hartree Fock results. The proposed transition-state method gives a direct connection between bond orders and bonding energies.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2sXmtVKqsb4%253D&md5=0fe2c10ffe695b99b56c5a9706d9e7bc
20. 20

    (a) Mitoraj, M.; Michalak, A. Donor–Acceptor Properties of Ligands from the Natural Orbitals for Chemical Valence. Organometallics 2007, 26, 6576,  DOI: 10.1021/om700754n

    20a

    Donor-Acceptor Properties of Ligands from the Natural Orbitals for Chemical Valence

    Mitoraj, Mariusz; Michalak, Artur

    Organometallics (2007), 26 (26), 6576-6580CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)

    Natural orbitals for chem. valence (NOCV) were used to characterize donor-acceptor properties of ligands in model Ni(II) complexes. NOCV allows for sepn. of ligand metal and metal ligand electron transfer processes (Dewar-Chatt-Duncanson model). Bonding between the ligand X = CN-, PH3, NH3, C2H4, CO, CS, N2, NO+ and the metal-contg. fragment in the [Ni L3]2+ complexes (L = NH3, CO) are discussed. For both σ-donation and π-back-bonding, the resulting orders of ligands are in a qual. agreement with those commonly accepted. However, also the influence of the metal-contg. fragment can be substantial, changing the relative donor-acceptor characteristics of different ligands.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXht1Wlt7bO&md5=de1a01f45074f685357537ef7d996164

    (b) Mitoraj, M.; Michalak, A. Applications of natural orbitals for chemical valence in a description of bonding in conjugated molecules. J. Mol. Model. 2008, 14, 681,  DOI: 10.1007/s00894-008-0276-1

    20b

    Applications of natural orbitals for chemical valence in a description of bonding in conjugated molecules

    Mitoraj, Mariusz; Michalak, Artur

    Journal of Molecular Modeling (2008), 14 (8), 681-687CODEN: JMMOFK; ISSN:0948-5023. (Springer GmbH)

    Natural orbitals for chem. valence (NOCV) were used to describe bonding in conjugated π-electron mols. The single C-C bond in trans-1,3-butadiene, 1,3-butadiene-1,1,4,4-tetra-carboxylic acid, 1,3,5,7-octatetraene, and 11-cis-retinal was characterized. In the NOCV framework, the formation of the σ-bond appears as the sum of two complementary charge transfer processes from each vinyl fragment to the bond region, and partially to the other fragment. The formation of the π-component of the bond is described by two pairs of NOCV representing the transfer of charge d. from the neighboring double C-C bonds. The NOCV eigenvalues and the related fragment-fragment bond multiplicities were used as quant. measures of the σ- and π- contributions. The σ-component of the single C-C bonds appears to be practically const. in the systems analyzed, whereas the π-contributions increase from butadiene (∼7.5%) to retinal (∼14%).

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtVKgtLs%253D&md5=516feb65b75240eae59116fdbcfc8d98
21. 21

    (a) ADF2017, SCM, Theoretical Chemistry, Vrije Universiteit, Amsterdam, The Netherlands, http://www.scm.com;

    There is no corresponding record for this reference.

    (b) te Velde, G.; Bickelhaupt, F. M.; Baerends, E. J.; Guerra, C. F.; van Gisbergen, S. J. A.; Snijders, J. G.; Ziegler, T. Chemistry with ADF. J. Comput. Chem. 2001, 22, 931,  DOI: 10.1002/jcc.1056

    21b

    Chemistry with ADF

    Te Velde, G.; Bickelhaupt, F. M.; Baerends, E. J.; Fonseca Guerra, C.; Van Gisbergen, S. J. A.; Snijders, J. G.; Ziegler, T.

    Journal of Computational Chemistry (2001), 22 (9), 931-967CODEN: JCCHDD; ISSN:0192-8651. (John Wiley & Sons, Inc.)

    A review with 241 refs. We present the theor. and tech. foundations of the Amsterdam D. Functional (ADF) program with a survey of the characteristics of the code (numerical integration, d. fitting for the Coulomb potential, and STO basis functions). Recent developments enhance the efficiency of ADF (e.g., parallelization, near order-N scaling, QM/MM) and its functionality (e.g., NMR chem. shifts, COSMO solvent effects, ZORA relativistic method, excitation energies, frequency-dependent (hyper)polarizabilities, at. VDD charges). In the Applications section we discuss the phys. model of the electronic structure and the chem. bond, i.e., the Kohn-Sham MO (MO) theory, and illustrate the power of the Kohn-Sham MO model in conjunction with the ADF-typical fragment approach to quant. understand and predict chem. phenomena. We review the "Activation-strain TS interaction" (ATS) model of chem. reactivity as a conceptual framework for understanding how activation barriers of various types of (competing) reaction mechanisms arise and how they may be controlled, for example, in org. chem. or homogeneous catalysis. Finally, we include a brief discussion of exemplary applications in the field of biochem. (structure and bonding of DNA) and of time-dependent d. functional theory (TDDFT) to indicate how this development further reinforces the ADF tools for the anal. of chem. phenomena.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXjtlGntrw%253D&md5=314e7e942de9b28e664afc5adb2f574f
22. 22

    (a) van Lenthe, E.; Baerends, E. J. Optimized Slater-type basis sets for the elements 1–118. J. Comput. Chem. 2003, 24, 1142,  DOI: 10.1002/jcc.10255

    22a

    Optimized Slater-type basis sets for the elements 1-118

    Van Lenthe, E.; Baerends, E. J.

    Journal of Computational Chemistry (2003), 24 (9), 1142-1156CODEN: JCCHDD; ISSN:0192-8651. (John Wiley & Sons, Inc.)

    Seven different types of Slater type basis sets for the elements H (Z = 1) up to E118 (Z = 118), ranging from a double zeta valence quality up to a quadruple zeta valence quality, are tested in their performance in neutral at. and diat. oxide calcns. The exponents of the Slater type functions are optimized for the use in (scalar relativistic) zeroth-order regular approximated (ZORA) equations. At. tests reveal that, on av., the abs. basis set error of 0.03 kcal/mol in the d. functional calcn. of the valence spinor energies of the neutral atoms with the largest all electron basis set of quadruple zeta quality is lower than the av. abs. difference of 0.16 kcal/mol in these valence spinor energies if one compares the results of ZORA equation with those of the fully relativistic Dirac equation. This av. abs. basis set error increases to about 1 kcal/mol for the all electron basis sets of triple zeta valence quality, and to approx. 4 kcal/mol for the all electron basis sets of double zeta quality. The mol. tests reveal that, on av., the calcd. atomization energies of 118 neutral diat. oxides MO, where the nuclear charge Z of M ranges from Z = 1-118, with the all electron basis sets of triple zeta quality with two polarization functions added are within 1-2 kcal/mol of the benchmark results with the much larger all electron basis sets, which are of quadruple zeta valence quality with four polarization functions added. The accuracy is reduced to about 4-5 kcal/mol if only one polarization function is used in the triple zeta basis sets, and further reduced to approx. 20 kcal/mol if the all electron basis sets of double zeta quality are used. The inclusion of g-type STOs to the large benchmark basis sets had an effect of less than 1 kcal/mol in the calcn. of the atomization energies of the group 2 and group 14 diat. oxides. The basis sets that are optimized for calcns. using the frozen core approxn. (frozen core basis sets) have a restricted basis set in the core region compared to the all electron basis sets. On av., the use of these frozen core basis sets give at. basis set errors that are approx. twice as large as the corresponding all electron basis set errors and mol. atomization energies that are close to the corresponding all electron results. Only if spin-orbit coupling is included in the frozen core calcns. larger errors are found, esp. for the heavier elements, due to the addnl. approxn. that is made that the basis functions are orthogonalized on scalar relativistic core orbitals.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXks1CrsbY%253D&md5=c81bd54b25e36fba1e659c5cf525ec12

    (b) van Lenthe, E.; Baerends, E. J.; Snijders, J. G. Relativistic regular two-component Hamiltonians. J. Chem. Phys. 1993, 99, 4597,  DOI: 10.1063/1.466059

    22b

    Relativistic regular two-component Hamiltonians

    van Lenthe, E.; Baerends, E. J.; Snijders, J. G.

    Journal of Chemical Physics (1993), 99 (6), 4597-610CODEN: JCPSA6; ISSN:0021-9606.

    In the present work, potential-dependent transformations were used to transform the four-component Dirac Hamiltonian into relativistic, effective, two-component, regular Hamiltonians. To zeroth order, the expansions give second-order differential equations (just like the Schroedinger equation), which already contain the most important relativistic effects, including spin-orbit coupling. One of the zeroth- order Hamiltonians is identical to the one obtained earlier by Ch. Chang, et al., (1986). By using these Hamiltonians, self-consistent all-electron and frozen-core calcns., as well as first-order perturbation calcns. were done for the uranium atom. They gave very accurate results, esp. for the one-electron energies and electron densities of the valence orbitals.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXmsl2jt7o%253D&md5=7825e27964bc3ff2093eb92a4285d3cc

    (c) van Lenthe, E.; Baerends, E. J.; Snijders, J. G. Relativistic total energy using regular approximations. J. Chem. Phys. 1994, 101, 9783,  DOI: 10.1063/1.467943

    22c

    Relativistic total energy using regular approximations

    van Lenthe, E.; Baerends, E. J.; Snijders, J. G.

    Journal of Chemical Physics (1994), 101 (11), 9783-92CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)

    In this paper we will discuss relativistic total energies using the zeroth order regular approxn. (ZORA). A simple scaling of the ZORA one-electron Hamiltonian is shown to yield energies for the hydrogenlike atom that are exactly equal to the Dirac energies. The regular approxn. is not gauge invariant in each order, but the scaled ZORA energy can be shown to be exactly gauge invariant for hydrogenic ions. It is practically gauge invariant for many-electron systems and proves superior to the (unscaled) first order regular approxn. for at. ionization energies. The superior to the (unscaled) first order regular approxn. for at. ionization energies. The regular approxn., if scaled, can therefore be applied already in zeroth order to mol. bond energies. Scalar relativistic d. functional all-electron and frozen core calcns. on diatomics, consisting of copper, silver, and gold and their hydrides are presented. We used exchange-correlation energy functionals commonly used in nonrelativistic calcns.; both in the local-d. approxn. (LDA) and including d.-gradient ("nonlocal") corrections (NLDA). At the NLDA level the calcd. dissocn. energies are all within 0.2 eV from expt., with an av. of 0.1 eV. All-electron calcns. for Au2 and AuH gave results within 0.05 eV of the frozen core calcns. Ag2 and AgCu and CuH.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXisFChu7g%253D&md5=4b0c97a476c22d4e3f783f0b97c72581
23. 23

    (a) Frenking, G.; Bickelhaupt, F. M. The Chemical Bond 1. Fundamental Aspects of Chemical Bonding, chap. The EDA Perspective of Chemical Bonding, 121. Wiley-VCH: Weinheim, 2014.

    There is no corresponding record for this reference.

    (b) Zhao, L. M.; von Hopffgarten; Andrada, D. M.; Frenking, G. WIREs Comput. Mol. Sci. 2018, 8, 1345

    There is no corresponding record for this reference.

    (c) Zhao, L.; Hermann, M.; Schwarz, W. H. E.; Frenking, G. The Lewis electron-pair bonding model: modern energy decomposition analysis. Nat. Rev. Chem. 2019, 3, 48,  DOI: 10.1038/s41570-018-0060-4

    23c

    The Lewis electron-pair bonding model: modern energy decomposition analysis

    Zhao, Lili; Hermann, Markus; Schwarz, W. H. Eugen; Frenking, Gernot

    Nature Reviews Chemistry (2019), 3 (1), 48-63CODEN: NRCAF7; ISSN:2397-3358. (Nature Research)

    A review. Breaking down the calcd. interaction energy between two or more fragments into well-defined terms enables a phys. meaningful understanding of chem. bonding. Energy decompn. anal. (EDA) is a powerful method that connects the results of accurate quantum chem. calcns. with the Lewis electron-pair bonding model. The combination of EDA with natural orbitals for chem. valence (NOCV) links the heuristic Lewis picture with quant. MO theory complemented by Pauli repulsion and Coulombic interactions. The EDA-NOCV method affords results that provide a phys. sound picture of chem. bonding between any atoms. We present and discuss results for the prototypical main-group diatomics H2, N2, CO and BF, before comparing bonding in N2 and C2H2 with that in heavier homologues. The discussion on multiply bonded species is continued with a description of B2 and its N-heterocyclic carbene adducts.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXnsFCmurk%253D&md5=7fcf5f6eb257e5f975912ff58e93bdd2

    (d) Yang, W.; Krantz, K. E.; Freeman, L. A.; Dickie, D.; Molino, A.; Frenking, G.; Pan, S.; Wilson, D. J. D.; Gilliard, R. J., Jr. Persistent Borafluorene Radicals. Angew. Chem., Int. Ed. 2020, 59, 3850,  DOI: 10.1002/anie.201909627

    23d

    Persistent Borafluorene Radicals

    Yang, Wenlong; Krantz, Kelsie E.; Freeman, Lucas A.; Dickie, Diane A.; Molino, Andrew; Frenking, Gernot; Pan, Sudip; Wilson, David J. D.; Gilliard, Robert J., Jr.

    Angewandte Chemie, International Edition (2020), 59 (10), 3850-3854CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    N-Heterocyclic carbene (NHC)- and cyclic (alkyl)(amino)carbene (CAAC)-stabilized 9-borafluorene radicals have been isolated and characterized by elemental anal., single-crystal X-ray diffraction, UV/Vis absorption, cyclic voltammetry (CV), ESR (EPR) spectroscopy, and theor. studies. Both the 9-CAAC-borafluorene radical (2) and the 9-IPr-borafluorene radical (4) have a considerable amt. of spin d. localized on the boron atoms (0.322 for 2 and 0.369 for 4). In compd. 2, the unpaired electron is also partly delocalized over the CAAC ligand and N atoms. However, the unpaired electron in compd. 4 mainly resides throughout the borafluorene π-system, with significantly less delocalization over the NHC ligand. These results highlight the Lewis base dependent electrostructural tuning of materials-relevant radicals. Notably, this is the first report of cryst. borafluorene radicals, and these species exhibit remarkable solid-state and soln. stability.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsFOgt7k%253D&md5=d25d0fc1380e2b5dda1c48532e7f64f9

    (e) Deng, G.; Pan, S.; Wang, G.; Zhao, L.; Zhou, M.; Frenking, G. Side-On Bonded Beryllium Dinitrogen Complexes. Angew. Chem., Int. Ed. 2020, 59, 10603,  DOI: 10.1002/anie.202002621

    23e

    Side-On Bonded Beryllium Dinitrogen Complexes

    Deng, Guohai; Pan, Sudip; Wang, Guanjun; Zhao, Lili; Zhou, Mingfei; Frenking, Gernot

    Angewandte Chemie, International Edition (2020), 59 (26), 10603-10609CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    The prepn. and spectroscopic identification of the complexes NNBe(η2-N2) and (NN)2Be(η2-N2) and the energetically higher lying isomers Be(NN)2 and Be(NN)3 are reported. NNBe(η2-N2) and (NN)2Be(η2-N2) are the first examples of covalently side-on bonded N2 adducts of a main-group element. The anal. of the electronic structure using modern methods of quantum chem. suggests that NNBe(η2-N2) and (NN)2Be(η2-N2) should be classified as π complexes rather than metalladiazirines.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXntFCktbc%253D&md5=0336f4f8d260e098dfca5f19a084c5b6

    (f) Pan, S.; Frenking, G. Comment on “Realization of Lewis Basic Sodium Anion in the NaBH₃– Cluster”. Angew. Chem., Int. Ed. 2020, 59, 8756,  DOI: 10.1002/anie.202000229

    23f

    Comment on "Realization of Lewis Basic Sodium Anion in the NaBH3- Cluster"

    Pan, Sudip; Frenking, Gernot

    Angewandte Chemie, International Edition (2020), 59 (23), 8756-8759CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    A polemic related to the work of G. Liu et al. (ibid., 2019, 131, 13927). We challenge the interpretation of the chem. bond in NaBH3- proposed by the authors. We argue that NaBH3- has an electron-sharing Na-BH3- covalent bond rather than a dative bond Na-→BH3.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXmsVSmsL8%253D&md5=cd08ec8a7d9a00da0b245ebcfbf99fad

    (g) Zhao, L.; Pan, S.; Zhou, M.; Frenking, G. Response to Comment on “Observation of alkaline earth complexes M(CO)₈ (M = Ca, Sr, or Ba) that mimic transition metals”. Science 2019, 365, eaay5021  DOI: 10.1126/science.aay5021

    There is no corresponding record for this reference.

    (h) Saha, R.; Pan, S.; Chattaraj, P. K.; Merino, G. Filling the void: controlled donor–acceptor interaction facilitates the formation of an M–M single bond in the zero oxidation state of M (M = Zn, Cd, Hg). Dalton Trans. 2020, 49, 1056,  DOI: 10.1039/C9DT04213J

    23h

    Filling the void: controlled donor-acceptor interaction facilitates the formation of an M-M single bond in the zero oxidation state of M (M = Zn, Cd, Hg)

    Saha, Ranajit; Pan, Sudip; Chattaraj, Pratim K.; Merino, Gabriel

    Dalton Transactions (2020), 49 (4), 1056-1064CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)

    The intriguing question of whether it is possible to form a genuine M0-M0 single bond for the M2 species (M = Zn, Cd, Hg) is addressed here. So far, all the bonds reported in the literature are exclusively MI-MI. Herein, we present viable M2(NHBMe)2 (M = Zn, Cd, Hg; NHBMe = (HCNMe)2B) complexes in which the controlled donor-acceptor interaction leads to an M0-M0 single bond. In these complexes, M2 in the 1.sum.g ground state with the (nσg+)2(nσu+)2 (n = 7, 10 and 14 for M = Zn, Cd and Hg, resp.) valence electron configuration forms donor-acceptor bonding with singlet 2NHBMe ligands where a combined effect of dominant (+,-) σ-back-donation from the antibonding (nσu+)2 orbital of M2 to the 2NHBMe ligands and a somewhat weaker (+,+) σ-donation from the 2NHBMe ligands to the bonding (n+1)σg+ orbital leads to the unorthodox bonding situation of forming an M-M single bond in the zero oxidn. state by eventually nullifying one effect by another. This is an unprecedented situation in the sense that the NHBMe ligand acts as a strong σ-acceptor and a weaker σ-donor. A comparison with the exptl. reported M2(PhDipp)2 complexes reveals the uniqueness of the NHBMe ligand in exhibiting such a bonding scenario. The M2(NHBMe)2 complex is thermochem. viable with respect to possible dissocn. channels at room temp., except for metal extrusion processes, M2(NHBMe)2 → M + M(NHBMe)2 and M2(NHBMe)2 → M2 + (NHBMe)2. Although the latter two processes are exergonic, they are kinetically protected by a high free energy barrier of 26.5-39.5 kcal mol-1. The exptl. characterization of M2(PhDipp)2 despite similar exergonic channels reveals such kinetic stability to be enough for the viability of the M2(NHBMe)2 complexes. Furthermore, the ligand exchange reaction considering M2(PhMe)2 as the starting material also turned out to be feasible. Therefore, the M2(NHBMe)2 complexes are the first cases that feature a neutral M2 moiety with a single M0-M0 covalent bond, where M is a Group 12 metal.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXit12hsb%252FP&md5=00521352090bd197fcbe73119f386523
24. 24

    (a) Andrés, J.; Ayers, P. W.; Boto, R. A.; Carbó-Dorca, R.; Chermette, H.; Cioslowski, J.; Contreras-García, J.; Cooper, D. L.; Frenking, G.; Gatti, C.; Heidar-Zadeh, F.; Joubert, L.; Martín Pendás, A.; Matito, E.; Mayer, I.; Misquitta, A. J.; Mo, Y.; Pilmé, J.; Popelier, P. L. A.; Rahm, M.; Ramos-Cordoba, E.; Salvador, P.; Schwarz, W. H. E.; Shahbazian, S.; Silvi, B.; Solà, M.; Szalewicz, K.; Tognetti, V.; Weinhold, F.; Zins, E. L. Nine questions on energy decomposition analysis. J. Comput. Chem. 2019, 40, 2248,  DOI: 10.1002/jcc.26003

    24a

    Nine questions on energy decomposition analysis

    Andres, Juan; Ayers, Paul W.; Boto, Roberto A.; Carbo-Dorca, Ramon; Chermette, Henry; Cioslowski, Jerzy; Contreras-Garcia, Julia; Cooper, David L.; Frenking, Gernot; Gatti, Carlo; Heidar-Zadeh, Farnaz; Joubert, Laurent; Martin Pendas, Angel; Matito, Eduard; Mayer, Istvan; Misquitta, Alston J.; Mo, Yirong; Pilme, Julien; Popelier, Paul L. A.; Rahm, Martin; Ramos-Cordoba, Eloy; Salvador, Pedro; Schwarz, W. H. Eugen; Shahbazian, Shant; Silvi, Bernard; Sola, Miquel; Szalewicz, Krzysztof; Tognetti, Vincent; Weinhold, Frank; Zins, Emilie-Laure

    Journal of Computational Chemistry (2019), 40 (26), 2248-2283CODEN: JCCHDD; ISSN:0192-8651. (John Wiley & Sons, Inc.)

    The paper collects the answers of the authors to the following questions:Is the lack of precision in the definition of many chem. concepts one of the reasons for the coexistence of many partition schemes. Does the adoption of a given partition scheme imply a set of more precise definitions of the underlying chem. concepts. How can one use the results of a partition scheme to improve the clarity of definitions of concepts. Are partition schemes subject to scientific Darwinism. If so, what is the influence of a community's sociol. pressure in the "natural selection" process. To what extent does/can/should investigated systems influence the choice of a particular partition scheme. Do we need more focused chem. validation of Energy Decompn. Anal. (EDA) methodol. and descriptors/terms in general. Is there any interest in developing common benchmarks and test sets for cross-validation of methods. Is it possible to contemplate a unified partition scheme (let us call it the "std. model" of partitioning), that is proper for all applications in chem., in the foreseeable future or even in principle. In the end, science is about expts. and the real world. Can one, therefore, use any expt. or exptl. data be used to favor one partition scheme over another.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXht1yntLrP&md5=774cc9356c1396950190cbca0c8cf2ea
25. 25

    (a) Yufit, D. S.; Howard, J. A. K.; Davidson, M. G. Bonding in phosphorus ylides: topological analysis of experimental charge density distribution in triphenylphosphonium benzylide. J. Chem. Soc., Perkin Trans. 2000, 2, 249,  DOI: 10.1039/A908099F

    There is no corresponding record for this reference.

    (b) Kulkarni, A.; Arumugam, S.; Francis, M.; Reddy, P. G.; Nag, E.; Gorantla, S. M. N. V. T.; Mondal, K. C.; Roy, S. Solid-State Isolation of Cyclic Alkyl(Amino) Carbene (cAAC)-Supported Structurally Diverse Alkali Metal-Phosphinidenides. Chem. – Eur. J. 2021, 27, 200

    25b

    Solid-State Isolation of Cyclic Alkyl(Amino) Carbene (cAAC)-Supported Structurally Diverse Alkali Metal-Phosphinidenides

    Kulkarni, Aditya; Arumugam, Selvakumar; Francis, Maria; Reddy, Pulikanti Guruprasad; Nag, Ekta; Gorantla, Sai Manoj N. V. T.; Mondal, Kartik Chandra; Roy, Sudipta

    Chemistry - A European Journal (2021), 27 (1), 200-206CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Cyclic alkyl(amino) carbene (cAAC)-supported, structurally diverse alkali metal-phosphinidenides 2-5 of general formula ((cAAC)P-M)n(THF)x [2: M = K, n = 2, x = 4; 3: M = K, n = 6, x = 2; 4: M = K, n = 4, x = 4; 5: M = Na, n = 3, x = 1] were synthesized by the redn. of cAAC-stabilized chloro-phosphinidene cAAC:P-Cl (1) using metallic K or KC8 and Na-naphthalenide as reducing agents. Complexes 2-5 were structurally characterized in solid state by NMR studies and single crystal x-ray diffraction. The proposed mechanism for the electron transfer process was well-supported by cyclic voltammetry (CV) studies and D. Functional Theory (DFT) calcns. The solid state oligomerization process is largely dependent on the ionic radii of alkali metal ions, steric bulk of cAAC ligands and solvation/de-solvation/recombination of the dimeric unit [(cAAC)P-M(THF)x]2.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisVyis7%252FI&md5=ecc39025fa1c367efd3e2d17f1109e54
26. 26

    Lloyd, D.; Sneezum, J. S. The preparation of some pyridinium cyclopentadienylides. Tetrahedron 1958, 14, 334,  DOI: 10.1016/0040-4020(58)80038-1

    There is no corresponding record for this reference.
27. 27

    (a) Matta, C. F.; Boyd, R. J. The Quantum Theory of Atoms in Molecules: From Solid State to DNA and Drug Design (Eds.:), Chapter 1. An Introduction to the Quantum Theory of Atoms in Molecules, Wiley: Hoboken, 2007, 1;

    There is no corresponding record for this reference.

    (b) Bader, R. F. W. Acc. Chem. Res. 1985, 18, 9,  DOI: 10.1021/ar00109a003

    27b

    Atoms in molecules

    Bader, R. F. W.

    Accounts of Chemical Research (1985), 18 (1), 9-15CODEN: ACHRE4; ISSN:0001-4842.

    A review with 21 refs.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2MXmtFGgsA%253D%253D&md5=602888ebc5fbe1c57b86efd88972306c

    (c) Bader, R. F. W. Chem. Rev. 1991, 94, 893

    There is no corresponding record for this reference.

    (d) Kumar, P. S. V.; Raghavendra, V.; Subramanian, V. J. Chem. Sci. 2016, 128, 1527,  DOI: 10.1007/s12039-016-1172-3

    27d

    Bader's Theory of Atoms in Molecules (AIM) and its Applications to Chemical Bonding

    Kumar, P.; Raghavendra, V.; Subramanian, V.

    Journal of Chemical Sciences (Berlin, Germany) (2016), 128 (10), 1527-1536CODEN: JCSBB5; ISSN:0974-3626. (Springer GmbH)

    A review. In this perspective article, the basic theory and applications of the "Quantum Theory of Atoms in Mols." have been presented with examples from different categories of weak and hydrogen bonded mol. systems. [Figure not available: see fulltext.].

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xhs1ajsrnF&md5=035ca1f3c58c76b8a4085659f7354ad8
28. 28

    (a) Zhang, Q.; Li, W. -L.; Xu, C.; Chen, M.; Zhou, M.; Li, J.; Andrada, D. M.; Frenking, G. Formation and Characterization of the Boron Dicarbonyl Complex [B(CO)₂]⁻. Angew. Chem., Int. Ed. 2015, 54, 11078,  DOI: 10.1002/anie.201503686

    28a

    Formation and Characterization of the Boron Dicarbonyl Complex [B(CO)2]-

    Zhang, Qingnan; Li, Wan-Lu; Xu, Cong-Qiao; Chen, Mohua; Zhou, Mingfei; Li, Jun; Andrada, Diego M.; Frenking, Gernot

    Angewandte Chemie, International Edition (2015), 54 (38), 11078-11083CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    The authors report the synthesis and spectroscopic characterization of the B dicarbonyl complex [B(CO)2]-. The bonding situation is analyzed and compared with the Al homolog [Al(CO)2]- using state-of-the-art quantum chem. methods.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1yqtbfN&md5=d530d68b6fbc8a72203657267a7adbf0

    (b) Andrada, D. M.; Frenking, G. Stabilization of Heterodiatomic SiC Through Ligand Donation: Theoretical Investigation of SiC(L)₂ (L=NHC^Me, CAAC^Me, PMe₃). Angew. Chem., Int. Ed. 2015, 54, 12319,  DOI: 10.1002/anie.201502450

    28b

    Stabilization of Heterodiatomic SiC Through Ligand Donation: Theoretical Investigation of SiC(L)2 (L=NHCMe, CAACMe, PMe3)

    Andrada, Diego M.; Frenking, Gernot

    Angewandte Chemie, International Edition (2015), 54 (42), 12319-12324CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Quantum chem. calcns. were carried out at the BP86/TZ2P+ level for the compds. SiC(L)2 with L = NHCMe, CAACMe, PMe3 (NHC=N-heterocyclic carbene, CAAC=cyclic (alkyl)aminocarbene). The optimized geometries exhibit a trans arrangement of the ligands L at SiC with a planar coordination when L = NHCMe and PMe3, while a twisted conformation is calcd. when L=CAACMe. The bending angle L-Si-C is significantly more acute than the angle L-C-Si. Both angles become wider with the trend PMe3<NHCMe<CAACMe. The latter trend is also found for the bond dissocn. energies of the reaction SiC(L)2→SiC+2 L, which have abs. values between De = 98-163 kcal mol-1. Calcns. suggest that the compds. SiC(L)2 have a very large first and second proton affinity, which takes place at the central carbon and silicon atoms, resp. Energy decompn. analyses indicate that the best description of the bonding situation in SiC(L)2 features a cumulenic carbon-carbon bond and a dative carbon-silicon bond L-C=Si←L at the center.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFyqur3E&md5=4070eefe700554e45fb8fc6c9839d77f

    (c) Mohapatra, C.; Kundu, S.; Paesch, A. N.; Herbst-Irmer, R.; Stalke, D.; Andrada, D. M.; Frenking, G.; Roesky, H. W. The Structure of the Carbene Stabilized Si₂H₂ May Be Equally Well Described with Coordinate Bonds as with Classical Double Bonds. J. Am. Chem. Soc. 2016, 138, 10429,  DOI: 10.1021/jacs.6b07361

    28c

    The Structure of the Carbene Stabilized Si2H2 May Be Equally Well Described with Coordinate Bonds as with Classical Double Bonds

    Mohapatra, Chandrajeet; Kundu, Subrata; Paesch, Alexander N.; Herbst-Irmer, Regine; Stalke, Dietmar; Andrada, Diego M.; Frenking, Gernot; Roesky, Herbert W.

    Journal of the American Chemical Society (2016), 138 (33), 10429-10432CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)

    The cyclic alkyl(amino) carbene stabilized Si2H2 has been isolated in the mol. form of compn. (Me-cAAC:)2Si2H2 (1) and (Cy-cAAC:)2Si2H2 (2) at room temp. Compds. 1 and 2 were synthesized from the redn. of HSiCl3 using 3 equiv of KC8 in the presence of 1 equiv of Me-cAAC: and Cy-cAAC:, resp. These are the first mol. examples of Si2H2 characterized by single crystal X-ray structural anal. Moreover, electrospray ionization mass spectrometry and 1H as well as 29Si NMR data are reported. Furthermore, the structure of compd. 1 has been investigated by theor. methods. The theor. anal. of 1 explains equally well its structure with coordinate bonds as with classical double bonds of a 2,3-disila-1,3-butadiene.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xht12gtbjL&md5=52b177ef1270099ee9216fb9ecff37e5

    (d) Scharf, L. T.; Andrada, D. M.; Frenking, G.; Gessner, V. H. The Bonding Situation in Metalated Ylides. Chem. – Eur. J. 2017, 23, 4422,  DOI: 10.1002/chem.201605997

    28d

    The Bonding Situation in Metalated Ylides

    Scharf, Lennart T.; Andrada, Diego M.; Frenking, Gernot; Gessner, Viktoria H.

    Chemistry - A European Journal (2017), 23 (18), 4422-4434CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Quantum chem. calcns. have been carried out to study the electronic structure of metalated ylides particularly in comparison to their neutral analogs, the bisylides. A series of compds. of the general compn. Ph3P-C-L with L being either a neutral or an anionic ligand were analyzed and the impact of the nature of the substituent L and the total charge on the electronics and bonding situation was studied. The charge at the carbon atom as well as the dissocn. energies, bond lengths, and Wiberg bond indexes strongly depend on the nature of L. Here, not only the charge of the ligand but also the position of the charge within the ligand backbone plays an important role. Independent of the substitution pattern, the NBO anal. reveals the preference of unsym. bonding situations (P=C-L or P-C=L) for almost all compds. However, Lewis structures with two lone-pair orbitals at the central carbon atom are equally valid for the description of the bonding situation. This is confirmed by the pronounced lone-pair character of the frontier orbitals. Energy decompn. anal. mostly reveals the preference of several bonding situations, mostly with dative and ylidic electron-sharing bonds (e.g., P→C--L). In general, the anionic systems show a higher preference of the ylidic bonding situations compared to the neutral analogs. However, in most of the cases different resonance structures have to be considered for the description of the "real" bonding situation.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXktVeqsrY%253D&md5=3a3c4bba00ebc3712230df07bf51d309

    (e) Hermann, M.; Frenking, G. Carbones as Ligands in Novel Main-Group Compounds E[C(NHC)₂]₂ (E=Be, B⁺, C²⁺, N³⁺, Mg, Al⁺, Si²⁺, P³⁺): A Theoretical Study. Chem. – Eur. J. 2017, 23, 3347,  DOI: 10.1002/chem.201604801

    28e

    Carbones as Ligands in Novel Main-Group Compounds E[C(NHC)2]2 (E=Be, B+, C2+, N3+, Mg, Al+, Si2+, P3+): A Theoretical Study

    Hermann, Markus; Frenking, Gernot

    Chemistry - A European Journal (2017), 23 (14), 3347-3356CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Quantum chem. calcns. of the main-group compds. E[C(NHCMe)2]2 (E=Be, B+, C2+, N3+, Mg, Al+, Si2+, P3+) were carried out using d. functional theory at the BP86/def2-TZVPP and BP86-D3(BJ)/def2-TZVPP levels of theory. The geometry optimization at BP86/def2-TZVPP gives equil. structures with two-coordinated species E and bending angles C-E-C between 152.5° (E=Be) and 110.5° (E=Al). Inclusion of dispersion forces at BP86-D3(BJ)/def2-TZVPP yields a three-coordinated beryllium compd. Be[C(NHCMe)2]2 as the only energy min. form. Three-coordinated isomers are found besides the two-coordinated energy min. for the boron and carbon cations B[C(NHCMe)2]2+ and C[C(NHCMe)2]22+. The three-coordinated form of the boron compd. is energetically lower lying than the two-coordinated form, while the opposite trend is calcd. for the carbon species. The theor. predicted bond dissocn. energies suggest that all compds. are viable species for exptl. studies. The x-ray structure of the benzoannelated homolog of P[C(NHCMe)2]23+ that was recently reported by Dordevic et al. agrees quite well with the calcd. geometry of the mol. A detailed bonding anal. using charge and energy decompn. methods shows that the two-coordinated neutral compds. Be[C(NHCMe)2]2 and Mg[C(NHCMe)2]2 possess strongly pos. charged atoms Be and Mg. The carbodicarbene groups C(NHCMe)2 serve as acceptor ligands in the compds. and may be sketched with dative bonds (NHCMe)2C←E→C(NHCMe)2 (E=Be, Mg). Dative bonds in which the carbones C(NHCMe)2 are donor ligands are suggested for (NHCMe)2C→E←C(NHCMe)2 (E=B+, Al+). The dications and trications possess electron-sharing bonds in which the bonding situation is best described [(NHCMe)2C]+-E-[C(NHCMe)2]+ (E=C, Si, N+, P+).

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXis1Sjur4%253D&md5=b05d66eead12984ba85c6ed43e6f54a6

    (f) Georgiou, D. C.; Zhao, L.; Wilson, D. J. D.; Frenking, G.; Dutton, J. L. NHC-Stabilised Acetylene—How Far Can the Analogy Be Pushed?. Chem. – Eur. J. 2017, 23, 2926,  DOI: 10.1002/chem.201605495

    28f

    NHC-Stabilised Acetylene-How Far Can the Analogy Be Pushed?

    Georgiou, Dayne C.; Zhao, Lili; Wilson, David J. D.; Frenking, Gernot; Dutton, Jason L.

    Chemistry - A European Journal (2017), 23 (12), 2926-2934CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)

    Exptl. studies suggest that the compd.(NHCbz)2C2H3 [(NHCbz) = benzylated N-heterocyclic carbenes] can be considered as a complex of a distorted acetylene fragment which is stabilized by benzoannelated N-heterocyclic carbene ligands (NHCbz)→(C2H2)←(NHCbz). A quantum chem. anal. of the electronic structures shows that the description with dative bonds is more favorable than with electron-sharing double bonds (NHCbz)=(C2H2)=(NHCbz).

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhs1eqsLg%253D&md5=deb44acb5732452733f389e5c848d814
29. 29

    (a) Dewar, M. J. S. A Review of the π-Complex Theory. Bull. Soc. Chim. Fr. 1951, 18, C79

    There is no corresponding record for this reference.

    (b) Chatt, J.; Ducanson, L. A. J. Olefin co-ordination compounds. Part III. Infra-red spectra and structure: attempted preparation of acetylene complexes. Chem. Soc. 1953, 2929,  DOI: 10.1039/JR9530002939

    There is no corresponding record for this reference.
30. 30

    (a) Schleyer, P. v. R.; Maerker, C.; Dransfeld, A.; Jiao, H.; Hommes, N. J. R. v. E. Nucleus-Independent Chemical Shifts: A Simple and Efficient Aromaticity Probe. J. Am. Chem. Soc. 1996, 118, 6317,  DOI: 10.1021/ja960582d

    30a

    Nucleus-independent chemical shifts: a simple and efficient aromaticity probe

    Schleyer, Paul v.R.; Maerker, Christoph; Dransfeld, Alk; Jiao, Haijun; van Eikema Hommes, Nicolaas J. R.

    Journal of the American Chemical Society (1996), 118 (26), 6317-6318CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)

    Nucleus-independent chem. shifts (NICS), the neg. of the abs. magnetic shieldings (in ppm) computed at the ab initio GIAO-HF/6-31 + G* level at ring centers (non-weighted means of the heavy atom coordinates), are proposed as a simple and efficient magnetic probe for characterizing aromaticity and antiaromaticity. For a series of five membered heterocycles, NICS correlate with arom. stabilization energies, magnetic susceptibility exaltations, and geometric criteria of aromaticity. Arom. compds. have neg. NICS (e.g., -9.7 for benzene and -15.1 for pyrrole), whereas antiarom. systems, in contrast, exhibit pos. NICS values (18.1 for pentalene and 27.6 for cyclobutadiene). In addn., NICS can characterize the individual rings in polycyclic arom. (e.g., -19.7 and -7.0 for the five- and seven-membered rings in azulene) and antiarom. (e.g., -2.5 and 22.5 for the six- and four-membered rings in benzocyclobutadiene) systems as well as the spherical aromaticity of cage compds., e.g., closo-B12H122- (-34.4) and the 1,3-dehydro-5,7-adamantanediyl dication (-50.1). The C60 NICS confirm that the 5-rings are paramagnetic and the 6-rings are diamagnetic, but the magnitudes are not large.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XjsFCis7Y%253D&md5=fd205be78733a8f593307d4863afb340

    (b) Chen, Z.; Wannere, C. S.; Corminboeuf; Puchta, R.; Schleyer, P. v. R. Nucleus-Independent Chemical Shifts (NICS) as an Aromaticity Criterion. Chem. Rev. 2005, 105, 3842,  DOI: 10.1021/cr030088+

    30b

    Nucleus-Independent Chemical Shifts (NICS) as an Aromaticity Criterion

    Chen, Zhongfang; Wannere, Chaitanya S.; Corminboeuf, Clemence; Puchta, Ralph; Schleyer, Paul von Rague

    Chemical Reviews (Washington, DC, United States) (2005), 105 (10), 3842-3888CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)

    A comprehensive review is presented on nucleus-independent chem. shift as a criterion for aromaticity.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtVGisrbF&md5=85a30c551bbbc0439ceab177216a14e3
31. 31

    Baryshnikov, G. V.; Minaev, B. F.; Pittelkow, M.; Nielsen, C. B.; Salcedo, R. Nucleus-independent chemical shift criterion for aromaticity in π-extended tetraoxa[8]circulenes. J. Mol. Model. 2013, 19, 847,  DOI: 10.1007/s00894-012-1617-7

    31

    Nucleus-independent chemical shift criterion for aromaticity in π-extended tetraoxa[8]circulenes

    Baryshnikov, Gleb V.; Minaev, Boris F.; Pittelkow, Michael; Nielsen, Christian B.; Salcedo, Roberto

    Journal of Molecular Modeling (2013), 19 (2), 847-850CODEN: JMMOFK; ISSN:0948-5023. (Springer)

    Recently synthesized π-extended sym. tetraoxa[8]circulenes that exhibit electroluminescent properties were calcd. at the d. functional theory (DFT) level using the quantum theory of atoms in mols. (QTAIM) approach to electron d. distribution anal. Nucleus-independent chem. shift (NICS) indexes were used to characterize the aromaticity of the studied mols. The tetraoxa[8]circulene mols. were found to consist of two antiarom. perimeters (according to the Hueckel "4n" antiaromaticity rule) that include 8 and 24 π-electrons. Conversely, NICS calcns. demonstrated the existence of a common π-extended system (distributed like a flat ribbon) in the studied tetraoxa[8]circulene mols. Thus, these sym. tetraoxa[8]circulene mols. provide examples of diatropic systems characterized by the presence of induced diatropic ring currents.

    >> More from SciFinder ^®

    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhs1ehtbs%253D&md5=6982811f0eb387fc66a36d19d0a00c8e