The reaction of 1,2-dithiol-o-carborane, under basic conditions, with appropriate organic dihalogenated compounds results in the formation of macrocycles incorporating 7,8-dicarba-nido-undecaborate or 1,2- dicarba-closo-dodecaborane units. The synthesis of some non-cyclic dicarborane compounds containing only one sulfur per cage directly bonded to the cluster is described. On the basis of the different behavior of the dithiolato compounds versus the monothiolato, a mechanism that explains the formation of partially degraded and non-degraded compounds is proposed. The molecular structure of tetramethylammonium 7,8-(3′,6′,9′-trioxaundecane-1′,11′ -dithiolato-SS′)-dicarba-nido-undecaborate has been determined. It crystallizes in space group P21/c with 4 formula units per cell. The cell dimensions are a=14.058(7), b=7.536(2), c=22.980(9) Å, β=99.41°. © 1990.