CATHODIC CLEAVAGE OF C-S AND C-P IN CARBORANYL DERIVATIVES

An electrochemical cathodic study of sulfur- and phosphorus-carbon sub stituted derivatives of o-carborane has shown that C-S and C-P bond fi ssion takes place. The 1,2-dithio- 1,2-dicarba-closo-dodecaborane(12) derivatives display a marked influence of the S,S'-noncluster linkage in their cathodic behavior. Shorter S,S' linkages, which produce more strained cycles, give cathodic waves at lower voltages (-1.2 V, Ag/AgC l) than the less strained ones (-1.7 V). These cathodic peaks are attr ibuted to an electrochemical process followed by a chemical one. The c ompounds with shorter linkages are converted to o-carborane, and no C- S retention has been observed. The compounds with longer linkages prov ide comparable amounts of o-carborane, 7,8-C2B9H12- and 7,8-SRS-7,8-C2 B9H10- These less strained compounds exhibit some C-S bond retention. The phosphorus derivatives, which are noncyclic, behave like the more strained S mesocycles described above. Only o-carborane is found among the products following the electrochemical process, and in no case ha s C-P retention taken place.