Novel families of three-component reversible redox cycles involving cage deformation via intramolecular redox reaction: Tetrathiolate-bridged dinuclear molybda- and tungstacarboranes

The synthesis and structural analysis of two novel families of three-compon ent reversible redox cycles [(C2B9H11)M(mu -SPh)(2)](2)(PPNn)-P-n (M = Mo, n = 2-, 2; 1-, 3; 0, 4; and M = W, n = 2-, 6; 1-, 7; 0, 8), where the cleav age and re-formation of the carborane cage C-C bond is observed during the redox reaction, are reported. Electronic saturation of the metal center (18 e center) and the lack of bulky substituents on the carborane cage suggest that the deformed carborane cages in 2.PPN2, 6.PPN2, and 7.PPN invoke a new kind of deformed cage ("semicloso" framework). The XPS results show that t he unprecedented competition for electron density between the metal center and the carborane cage is involved in the cleavage and formation of the car borane C-C bond.