Gas phase structure of tetramethylethylene

Carlos, Jose L.; Bauer, S. H.

doi:10.1039/f29747000171

Cited by 8 publications

(1 citation statement)

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“…Mulliken analyses indicate strong spin localisation at the three atoms nearest neighbours to each vacancy, the most stable of many possible spin distributions leading to local moments of (+0.77 |e|, +0.77 |e|, -0.56 |e|) around one vacancy and moments of the opposite sign around the other, so that the total S z is zero. The A 1 -A 2 and A 1 -B 1 (and equivalent) distances of 1.345Å and 1.521Å, respectively, are close to electron diffraction values of 1.351Å and 1.516Å reported for TME 58 , while the double bond distance is also close to that of 1.325Å, which is calculated for (molecular) ethylene using an identical basis set and functional, whereas the next C-C distances away from the defect essentially coincide with the perfect bulk value of 1.560Å. The local geometries of the other spin states are close to that of the singlet.…”

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confidence: 84%

Looking for $$sp^2$$ s p 2 carbon atoms in diamond: a quantum mechanical study of interacting vacancies

et al. 2018

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This paper reports the calculated relaxed lattice configurations and corresponding electronic and magnetic structures, and Raman frequencies of two divacancies in diamond, V2 and VC=CV, in which the vacancies are first and third neighbours respectively. The calculations are formulated within a supercell approach to local defects in crystalline solids, here 64-and 128-atoms unit cells and based largely on the B3LYP one-electron approximation constructed from an all-electron Gaussian basis set. Three important findings are first, that, of the four possible spin states, Sz=0, 1, 2, 3, the singlet is predicted to be lowest in energy for both divacancies; second, that the singlet state of V2 is ∼1.7 eV lower in energy than that in VC=CV; and third, that the Raman peak at 1628 cm −1 in defective diamond can be ascribed to the presence of a C=C double bond, as in the singlet state of VC=CV.

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Section: Computational Detailssupporting

confidence: 84%

Looking for $$sp^2$$ s p 2 carbon atoms in diamond: a quantum mechanical study of interacting vacancies

et al. 2018

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Elektronendomänen und das VSEPR‐Modell der Molekülgeometrie

Gillespie

Robinson

1996

Angewandte Chemie

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Electron Domains and the VSEPR Model of Molecular Geometry

Gillespie

Robinson

1996

Angew. Chem. Int. Ed. Engl.

220

150

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The valence shell electron pair repulsion (VSEPR) model-also known as the Gillespie-Nyholm rules-has for many years provided a useful basis for understanding and rationalizing molecular geometry, and because of its simplicity it has gained widespread acceptance as a pedagogical tool. In its original formulation the model was based on the concept that the valence shell electron pairs behave as if they repel each other and thus keep as far apart as possible. But in recent years more emphasis has been placed on the space occupied by a valence shell electron pair, called the domain of the electron pair, and on the relative sizes and shapes of these domains. This reformulated version of the model is simpler to apply, and it shows more clearly that the Pauli principle provides the physical basis of the model. Moreover, Bader and his co-workers' analysis of the electron density distribution of many covalent molecules have shown that the local concentrations of electron density (charge concentrations) in the valence shells of the atoms in a molecule have the same relative locations and sizes as have been assumed for the electron pair domains in the VSEPR model, thus providing further support for the model. This increased understanding of the model has inspired efforts to examine the electron density distribution in molecules that have long been regarded as exceptions to the VSEPR model to try to understand these exceptions better. This work has shown that it is often important to consider not only the relative locations and sizes, but also the shapes, of both bonding and lone pair domains in accounting for the details of molecular geometry. It has also been shown that a basic assumption of the VSEPR model, namely that the core of an atom underlying its valence shell is spherical and has no influence on the geometry of a molecule, is normally valid for the nonmetals but often not valid for the metals, including the transition metals. The cores of polarizable metal atoms may be nonspherical because they include nonbonding electrons or because they are distorted by the ligands, and these nonspherical cores may have an important influence on the geometry of a molecule.

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Gas phase structure of tetramethylethylene

Cited by 8 publications

References 0 publications

Looking for $$sp^2$$ s p 2 carbon atoms in diamond: a quantum mechanical study of interacting vacancies

Looking for $$sp^2$$ s p 2 carbon atoms in diamond: a quantum mechanical study of interacting vacancies

Elektronendomänen und das VSEPR‐Modell der Molekülgeometrie

Electron Domains and the VSEPR Model of Molecular Geometry

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