Structure and inversion potential of thianthren
- 1 January 1975
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics
- Vol. 71, 1173-1182
- https://doi.org/10.1039/f29757101173
Abstract
A least squares reduction of the scattered intensity pattern, pM(p), [p(60/λ) sin θ/2], of thianthren assuming C2v symmetry, undistorted benzene rings and planar C6H4S2 groups gave the following rg values: 〈C—C〉= 1.400(2)Å, (C—S)= 1.770(3)Å, (C—H)= 1.082(22)Å, θ(dihedral angle)= 131.4(3)° with σ= 0.029 0. Models with slightly distorted benzene rings or non-planar C6H4S2 groups did not give an improved fit to the diffraction data. Comparisons are presented of the available structural data for thianthren and related molecules. A complete normal mode analysis was carried out to investigate the inversion and twisting motions of thianthren. It was concluded that the assumption of small harmonic vibrations did not adequately represent these motions. A number of models were tested assuming an inversion barrier of the form A(ϕ4–Bϕ2), [ϕ(π–θ)/2]; the best of these gave V0 4 kcal mol–1 for the inversion barrier and θ0= 128–130° for the dihedral angle at the energy minimum.Keywords
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