The Structure of Trithiapentalenes and Related Compounds

Abstract

Trithiapentalene is a representative of a large group of compounds where the three sulfur atoms can be substituted by sulfur, selenium, tellurium or oxygen, and the carbon atoms can be substituted by nitrogen.

The first representative of these compounds was prepared in 1925 and the structure has since been under debate.

A bicyclic naphthalene-like structure was proposed in the fifties, but the question was raised whether the observed properties were best explained by assuming this bicyclic structure or by assuming a tautomeric equilibrium between two shortlived monocyclic tautomers. During the last 15 years modern physicochemical methods have provided answers to most structural questions. Methods such as x-ray crystallography, ESCA spectroscopy, 1-H and 13-C NMR spectroscopy in anisotropic phases, mass spectroscopy, microwave spectroscopy and electron diffraction have been used in the structure elucidation.

Analogue compounds with more than 3 sulfur atoms raise corresponding structural problems.