SYNTHESES AND NMR-STUDIES OF MONO ALKYNE COMPLEXES OF MOLYBDENUM AND TUNGSTEN

Reactions of [MCl(CO)(PhC = CPh)(eta-5-C5H5)] (M = Mo, 1a; W, (1b)) with TISR (R = Me, Et, (n)Pr, (i)Pr and (t)Bu) give thiolate complexes [MSR(CO)(PhC = CPh)(eta-n-C5H5)] which according to IR and NMR spectroscopy exist in two isomeric forms as a result of restricted rotation about the M-SR bond. Reactions of [WCl(CO)(PhC = CPh)(eta-5-C5H5)] and metal salts ML-L, {ML-L = T1S2-Ph, T1S4-Py, Tlacac, TlOAc, T1S2P(OMe)2} (acac = 2,4-pentanedionato, Py = C5H4N) give similar monoalkyne complexes [WL-L(CO)(PhC = CPh)(eta-5-C5H5)] (3) in which the L-L species functions as a monodentate ligand. In contrast 1a and 1b react with NaS2CNMe2.2H2O to give carbonyl-free derivatives [M(S2CNMe2)(PhC = CPh)(eta-5-C5H5)] containing a bidentate dithiocarbamate ligand. Oxidation of [W{S2P(OMe)2}(CO)(PhC = CPh)(eta-5-C5H5)] in air gives the oxo complex [W{S2P(OMe)2}(O)-(PhC = CPh)(eta-5-C5H5)], thought to contain a monodentate S2P(OMe)2 ligand.