Molecular shapes of thianthrene and related heterocyclic compounds

Abstract

From data so far accumulated on three-membered heteroeyclie compounds derived by replacing anthracene meso CH groups by atoms A and B, it is pointed out that molecules are planar if both A and B are any of C, N or O, but folded if at least one of A and B is S, Se or Te. This difference is explained by taking account of d orbitals in S and S-like atoms. The folding of the molecule is due to the 'natural' valency angle of a S atom, as was pointed out by Lynton & Cox in the case of thianthrene. The folding angle is not much affected in a and fl thianthrene dioxide and thianthrene tetraoxide.