A symmetrically substituted thiathiophthen with unequal sulphur–sulphur bond lengths : crystal and molecular structure of 3,4-diphenyl-6a-thiathiophthen {3,4-diphenyl[1,2]dithiolo[1,5-b][1,2]dithiole-7-SIV}

Abstract

The molecular structure of the title compound (III) has been determined by single-crystal X-ray analysis. Crystals are monoclinic, with a= 13.924(13), b= 6.842(8), c= 15.350(13)Å, and = 90° 45′(4′), Z= 4, space group P2₁/c. The structure was solved by the symbolic-addition method and refined to R 0.104 on 1 527 non-zero diffractometer reflections. This symmetrically substituted thiathiophthen occupies a crystallographically general position and has decidedly unequal S–S bond lengths [2.236(4) and 2.430(4)Å] and rather short ‘external’ C–S bond lengths [1.649(12) and 1.653(12)Å]. Molecular dimensions give some indication of intramolecular strain. Correspondence of the X-ray results with those obtained by ESCA is discussed.