THE DESIGNED SYNTHESIS AND CHARACTERIZATION OF 2 NOVEL HETEROMETALLIC TRINUCLEAR INCOMPLETE CUBANE-LIKE CLUSTERS [(CH3CH2)4N](M2CUS4)(S2C2H4)2(PPH3) (M = MO, W)

Two novel heterometallic trinuclear incomplete cubane-like clusters [(CH3CH2)4N][{M2CuS4}(edt)2(PPh3)] (M = Mo, W) have been synthesized by reaction of [(CH3CH2)4N]2[M2S4(edt)2] (M = Mo, W) with Cu(PPh3)2(dtp) [where edt is 1,2-ethane-dithiolato ligand, dtp is S2P(OCH2CH3)2-]. The two crystals are isomorphous in space group P1 (No. 1). The unit cell contains two independent molecules, but the two discrete anions have the same orientation for the PPh3 ligands along one axis so the space group is undoubtedly non-centrosymmetric. The discrete anion contains two edt ligands and one PPh3 ligand attached to one incomplete cubane-like cluster core {M2CuS4}3+ (M = Mo, W). The bond lengths of Mo-Mo[W-W] and the two Mo-Cu[W-Cu] are 2.852(2)[2.844(1)], 2.802(2)[2.765(3)], 2.760(2)[2.762(3)] angstrom, respectively. The M2S4(edt)2 (M = Mo, W) moiety remains almost unchanged, except that for the compound 1 the Mo = S double bond length elongates from av. 2.10 to av. 2.165 angstrom. The title clusters provide a new type of unsymmetric mu-2-bridging sulphido ligand. The incomplete cubane-like cluster core {Mo2CuS4}3+ of compound 1 is distorted because the two Cu-mu-2-S bond lengths are significantly different (2.313 angstrom and 2.409 angstrom), but the core {W2CuS4}3+ of compound 2 has approximately C(s) symmetry. The IR spectra of the two title clusters and two starting materials are assigned.