The reaction of the complex OsHCl(CO)-(PiPr(3))(2) (1) With nBuLi in hexane affords OsH2(eta(2)-CH2=CHEt)(CO)(PiPr(3))(2) (2) which reacts with CS2 to give OsH(eta(2)-S2CH)(CO)(PiPr(3))(2) (3) The reaction of 3 with HBF4.OEt(2) Leads to two different derivatives depending upon the nature of the solvent used. The dihydrogen compound [Os(eta(2)-S2CH)(eta(2)-H-2)(CO)(PiPr(3))(2)]-BF4 (4) is formed in dichloromethane-d(2), while the methanedithiolate complex [OsH(eta(2)-S2CH2)(CO)(PiPr(3))(2)]-BF4 (5) is obtained in diethyl ether.