Multimetallic complexes of molybdenum(II) and tungsten(II) derived from [WI2(CO){PhP(CH(2)CH(2)PPh(2))(2)-P,P'}(eta(2)-RC(2)R)] (R=Me or PH). Crystal structures of [WI2(CO){PhP(CH(2)CH(2)PPh(2))(2)-P,P'}(eta(2)-MeC(2)R)] (R=Me or Ph)

Equimolar quantities of [WI2(CO)(NCMe)(eta(2)-RC(2)R')(2)] (R = R' = Me or Ph; R = Me, R' = Ph) and PhP(CH(2)CH(2)PPh(2))(2) (L) reacted in CH2Cl2 at room temperature to give the mono(alkyne) complexes [WI2(CO)(L-P,P')(eta(2)-RC(2)R')] in high yield. The molecular structures of [WI2(CO)(L-P,P')(eta(2)-MeC(2)R)] (R = Me or Ph) have been crystallographically determined. There are two independent molecules in the asymmetric unit which are diastereoisomers. The co-ordination pattern about the metal atom in [WI2(CO)(L-P,P')(eta(2)-MeC(2)Me)]. 0.75CH(2)Cl(2) 1 is a distorted octahedron with two adjacent phosphorus atoms of the triphosphine, a carbonyl and an iodide ligand in the equatorial plane and an iodide and the but-2-yne ligand occupying axial sites. The complex [WI2(CO)(L-P,P')(eta(2)-MeC(2)Ph)] is also a distorted octahedron, with identical co-ordination to that of 1, except in that the but-2-yne ligand is substituted by the 1-phenylprop-1-yne ligand. In 1 there is a pendant arm of the triphosphine ligand free to co-ordinate with other species. The reactions of the complexes [WI2(CO)(L-P,P')(eta(2)-RC(2)R)] (R = Me or Ph) as monodentate phosphine ligands with the molybdenum(II) and tungsten(II) complexes [MI(2)(CO)(3)(NCMe)(2)], [MI(2)(CO)(3)(NCMe)L'](L' = PPh(3), AsPh(3) or SbPh(3)), [MoCl(GeCl3)(CO)(2)(NCMe)(2)(PPh(3))] and [WI2(CO)(NCMe)(eta(2)-RC(2)R)(2)] (R = Me or Ph) were found to give a range of bi- and tri-metallic complexes which have all been characterised.