Unprecedented tetrathiolate-bridged dinuclear ionic molybdacarbaboranes [(C2B9H11)Mo(SPh)(2)](2)(n-) (n = 2, 1) are prepared by successive oxidation of [(C2B9H11)Mo-II-(CO)(2)(SPh)(2)](2-) with diphenyl disulfide and iodosylbenzene: X-ray crystal structure determinations and NMR studies show unusual scission and reformation of the C-C carbaborane cage bond.