On the charge distribution in ethanes and disilanes and correlations with equilibrium bond lengths; an ab initio study

Palmer, Michael H.

doi:10.1016/s0166-1280(00)00391-2

Cited by 12 publications

(2 citation statements)

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“…A previous study has drawn attention to the similarities and differences between these two (and other) methods . For some silane derivatives, the total integrated ED is not easily interpreted by standard electronegativity considerations; this has been attributed to how the core electrons are treated. , The positions of the CP in comparison to the respective covalent radii (CR) is appropriate. Although several series of CR are used, some widely used values for H, C, N, O, F, and Si atoms are 25, 67, 56, 48, 42, and 110 pm.…”

Section: Resultsmentioning

confidence: 99%

“…21 For some silane derivatives, the total integrated ED is not easily interpreted by standard electronegativity considerations; this has been attributed to how the core electrons are treated. 20,21 The positions of the CP in comparison to the respective covalent radii (CR) is appropriate. Although several series of CR are used, some widely used values 22 However, the two methods are making quite different summations; the summation over the "atomic basins" includes density from the "tail" of that on the neighboring atom(s).…”

Section: The Energy Surface For Sincmentioning

confidence: 99%

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The Molecular Structure of Methylfluoroisocyanato Silane: A Combined Microwave Spectral and Theoretical Study

et al. 2015

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The structure of methylfluoroisocyanato silane (Me-SiHF-NCO) has been deduced by a combination of microwave (MW) spectra including data from (12,13)C, (14,15)N, and (28,29,30)Si isotopomers, and ab initio calculations. The rotational constants (RC) for the most abundant isotopes are A = 6301.415(45), B = 1535.078(39), and C = 1310.485(39) MHz. The symmetric quartic centrifugal distortion constants have been identified, using the I(r) representation for C1 symmetry, which includes the 3-fold rotor. The spectra of the isotopomer combinations gave a partial substitution structure where the C2Si3, Si3N4, and N4C9 bond lengths are 1.8427(70), 1.7086(77), and 1.2120(90)Å; although the C2Si3N4 angle is close to tetrahedral (109.71° (52)), the Si3N4C9 angle is wide (157.69° (18)). The rotational constants are only consistent with a trans-orientation for each of the dihedral angles (HC2Si3N4, C2Si3N4C9, and Si3N4C9O10). The structural analysis was completed by calculations of the equilibrium structure, using MP3 in conjunction with an aug-cc-pVTZ basis set (434 Cartesian basis functions). This gave A = 6240.324, B = 1518.489, and C = 1297.819 MHz. The equilibrium structure bond lengths for C2Si3, Si3N4, and N4C9 were 1.8485, 1.7147, and 1.1947 Å, with the C2Si3N4 and Si3N4C9 angles 109.55 and 156.67°, respectively. Although the SiNC polynomial bending surface is complex, the data points can be fit to the simple form V(x) = 50.36(91)x(4) - 7.53(44)x(5), with comparatively little loss of accuracy. The A-rotational constant is strongly influenced by the Si3N4C9 angle, and smaller bases lead to this angle being nearly linear. The theoretical results suggest a very heavily polarized molecule, which is supported by the positions of the local electron density minima within the bonds and electron density calculations.

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Section: Resultsmentioning

confidence: 99%