Decarbonylationof triosmiummethylthiolato cluster OS3(CO)IO(J.l-H)(J.l-SMe) with Me3NO in acetonitrile solution gave cluster OS3(COMNCMe){J.l-H){J.l-SMe) (1), in which one axial CO on the non-bridged Os atom is replaced by an acetonitrile ligand. Crystal data for Z: space group P bca, a = 14.491 (I), b ;:;16.107(5), c =16.639(5) A, Z =8; R F =0.037, R, =0.033. Treatment of 2 with CpW(CO)3H in refluxing THF solution yielded two cluster compounds with formula CpWOs3(CO)1l(Il-HMIl3-SMe) (2) and CpWOsiCO)lJijJ.-HMfl-SMe) (3) as the principle products. The first possesses a spiked-triangular geometty with a triply bridging thiolato ligand and the second adopts a burterfly metal core arrangement with an edge-bridging thiolato grouping. The structure of 2 was characterized by single-crystal X-ray diffraction.Crystal data: space group P T, a = 8.865 (5), b;:; 8.959(3), c = 16.688(4) A, (X = 103.49(2),~= 93.58(3), ' Y = 113.03(4)", Z == 2, R F = 0.034, R", = 0.035.