A critical survey on the preferred conformations of diphenyl disulphone, dimethyl- and diphenyl-dichalcogenides, bis(3-thienyl)-disulphide and -disulphone

Abstract

A detailed analysis of the dipole moments of diphenyl disulphone as a benzene solute showed that the compound in solution exists as an equimolecular mixture of ψ-enantiomers characterized by a (O 2)S–S(O 2) rotational angle of ψ=118° in modulum, whilst in the crystal phase the molecules exhibit the s- trans structure ( ψ=180°) (C.H. Kiers, A. Vos, Rec. Trav. Chim. Pays-Bas 91 (1972) 126). Also from a dipole moment analysis, the preferred conformations in solution of dimethyl- and diphenyl-dichalcogenides, R 2X 2 with X=S, Se or Te, are determined and the results compared with previous studies. The actual structures of all these compounds in the non-condensed phase can be explained on classical grounds, at least qualitatively. The 1H and 13C NMR spectra of various 3-thienyl sulphides and sulphones, disulphides and disulphones including bis(3-thienyl)-disulphide and -disulphone, two novel compounds, were recorded and analysed in terms of the sulphur or sulphonyl mesomeric effect. Rotational isomerism for these compounds is also discussed, in the light for the sulphones of a molecular modelling for bis(3-thienyl) disulphone.