Treatment of MHCl(CO) (PPh(3))(3) (M = Ru, Os) with (CH2=CH) SnR(3) is a good general route to the coordinatively unsaturated osmium and ruthenium stannyl complexes M(SnR(3))Cl(CO)(PPh(3))(2) (1: M = Ru,R = Me;2: M = Ru, R = n-butyl; 3: M = Ru, R = p-tolyl; 4: M = Os, R = Me). These coordinatively unsaturated complexes readily add CO and CN-p-tolyl to form the coordinatively saturated compounds Mt SnR(3))Cl(CO)L(PPh(3))(2) (5: M =Ru, R = Me, L = CO;arM = Ru, R = n-butyl, L= CO; 7: M = Ru, R = p-tolyl, L = CO; 8: M = Os, R = Me, L = CO; 9: M = Ru, R = Me, L = CN-p-tolyl; 10: M = Ru, K = n-butyl, L = CN-p-tolyl; 11: M = Os, R = Me, L= CN-p-tolyl). In addition, the chloride ligand in Ru(SnR(3))Cl(CO) (PPh(3))(2) proves to be labile and treatment with the potentially bidentate anionic ligands, dimethyldithiocarbamate or diethyldithiocarbamate, affords the coordinatively saturated compounds Ru(SnR(3))(eta(2)-S(2)CNR'(2)) (CO) (PPh(3))(2) (12: R = Me, R' = Me; 13: R = Me, R' = Et; 14: R = n-butyl, R' = Me; 15: R =p-tolyl, R' = Me; 16: R =p-tolyl, R' = Et). Chloride is also displaced by carboxylates forming the six-coordinate compounds Ru(SnR(3)) (eta(2)-O(2)CR') (CO) (PPh(3))(2) (17: R = Me, R' = H; 18: R = Me, R' = Me; 19: R = Me, R' = Ph; 20: R = n-butyl, R' = Me; 21: R =p-tolyl, R' = Me). IR and H-1 NMR spectral data for all the new compounds and P-31 and Sn-119 NMR spectral data for selected compounds are reported.