Oxidation products of cesium monomercaptoundecahydro-closo-dodecaborate(2 -)

Abstract When an aqueous solution of boron-10-enriched cesium monomercaptoundecahydro- closo -dodecaborate(2 -), Cs 2 10 B 12 H 11 SH ( 1b ) was allowed to stand for a long period in contact with air, several oxidation products, separable by HPLC, were formed. Disulfide Cs 4 10 B 12 H 11 SS 10 B 12 H 11 ( 2b ), thiolsulfinate Cs 4 10 B 12 H 11 SSO 10 B 12 H 11 ( 3b ), and sulfinylsulfone Cs 4 10 B 12 H 11 SOSO 2 10 B 12 H 11 ( 4b ) were prepared stepwise by the reaction of the thiol Cs 2 10 B 12 H 11 SH ( 1b ) with an oxidizing agent. Oxidation of disulfide 2b with an equivalent amount of m -chloroperbenzoic acid (MCPBA) quantitatively gave the thiolsulfinate, 3b . Further oxidation proceeded on treating 3b with an excess of MCPBA. When two equivalents of MCPBA were used, the sulfinylsulfone 4b was formed predominantly and isolated as the cesium salt. The characterization of the oxidation products is described.