Synthesis of cyclic and polymeric derivatives of 1,2-dithiol-o-carborane

Abstract

Cyclic compounds containing two symmetrically placed 1,2-dicarbaclosododecaboranyl or two 7,8-dicarbaundecaborate(10) moieties have been synthesized. The bridges between the carborane cages are S---S or S---CH2---CH2---S for the undegraded species, and S---CH2---S or S---CH2CH2---S for the degraded ones. The sulfur atoms in all cases are bonded to the carbonate carbons. Unlike preparations previously reported in the literature, degradation to the partially degraded o-carborane cages proceeds without requiring treatment by a conventional base. Ring closure and the presence of sulfur atoms linked to the o-carborane carbons are believed to be necessary in order for the degradation to occur. When the number of bonds involved in the bridge between the two cages was seven, no cyclization occurred despite the presence of a square planar nickel template, the reaction instead producing a polymeric material.