Artigo Revisado por pares

Molecular Structure and Molecular Vibrations of 1,3,5,7,-Tetramethyl-2,4,6,8,9,10- Hexathiaadamantane

1998; American Chemical Society; Volume: 102; Issue: 2 Linguagem: Inglês

10.1021/jp972828m

ISSN

1520-5215

Autores

Gergely Szász, Attila Kovács, István Hargittai, Ingyu Jeon, Glen P. Miller,

Tópico(s)

Structural and Chemical Analysis of Organic and Inorganic Compounds

Resumo

The molecular structure and vibrations of 1,3,5,7,-tetramethyl-2,4,6,8,9,10-hexathiaadamantane have been determined by a joint computational, gas-phase electron diffraction, and spectroscopic investigation. The geometry and harmonic force field of the molecule was calculated at the Becke3-Lee-Yang-Parr/6-31G* level. Vibrational analysis was performed using FT-IR and FT-Raman spectra recorded in the 4000−150 cm-1 range and utilizing Pulay's DFT-based scaled quantum mechanical (SQM) method (DFT: density-functional theory). This SQM method was extended to molecules containing C−S structural motifs. The joint computational and electron diffraction analysis resulted in an equilibrium geometry of Td symmetry characterized by staggered orientation of the methyl groups with respect to their adjacent C−S bonds. The electron diffraction study yielded the following bond lengths (rg) and bond angles (with estimated total errors): C−S, 1.820 ± 0.004 Å; C−C, 1.536 ± 0.004 Å; C−H, 1.119 ± 0.005 Å; C−S−C, 102.2 ± 0.2°; H−C−H, 109.9 ± 0.7°. The barrier to methyl rotation was computed to be 17 kJ/mol in good agreement with that estimated from the average methyl torsion (with respect to the staggered form) of 10 ± 3° from the electron diffraction analysis.

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