Reactions of [M(SR)(3)(PMe2Ph)(2)] (M = Ru, Os; R = C6F4H-4, C6F5) with CS2 in acetone afford [Ru(S2CSR)(2)(PMe2Ph)(2)] (R = C6F4H-4, 1; C6F5, 3) and trans-thiolates [Ru(SR)(2)(S2CSR)(PMe2Ph)(2)] (R = C6F4H-4, 2; C6F5, 4) or the isomers trans-thiolates [Os(SR)(2)(S2CSR)(PMe2Ph)(2)] (R = C6F4H-4, 5; C6F5, 7) and trans-thiolate-phosphine [Os(SR)(2)(S2CSR)(PMe2Ph)(2)] (R = C6F4H-4, 6; C6F5, 8) through processes involving CS2 insertion into M-SR bonds. The ruthenium(Ill) complexes [Ru(SR)(3)(PMe2Ph)(2)] react with CS2 to give the diamagnetic thiolate-thioxanthato ruthenium(II) and the paramagnetic ruthenium(III) complexes while osmium(III) complexes [Os(SR)(3)(PMe2Ph)(2)] react to give the paramagnetic thiolate-thioxanthato osmium(III) isomers. The single-crystal X-ray diffraction studies of 1, 4, 5, and 8 show distorted octahedral structures. P-31 {H-1} and F-19 NMR studies show that the solution structures of 1 and 3 are consistent with the solid-state structure of 1.