Disulfuration and hydrosulfuration of alkynes mediated by an unusual square-planar tetrathiolate cobalt(III) complex [CP2Co](+)[Co(S2C2B10H10)(2)](-), 1, lead to a series of cobalt-free carboranyl vinyl sulfides 2-9. All new complexes 1, 2, 3, 4, 5, 6, 7, 8, and 9 were characterized by NMR spectroscopy (H-1, B-11, C-13), and X-ray structural analyses were performed for 1, 2, 3, 5, 6, 7, and 9.