Multimetallic complexes of molybdenum(II) and tungsten(II) derived from [WI2(CO){PhP(CH2CH2PPh2)2-P,P′}(η2-RC2R)](R = Me or Ph). Crystal structures of [WI2(CO){PhP(CH2CH2PPh2)2-P,P′}(η2-MeC2R)](R = Me or Ph)

Abstract

Equimolar quantities of [WI₂(CO)(NCMe)(η²-RC₂R′)₂](R = R′= Me or Ph; R = Me, R′= Ph) and PhP(CH₂CH₂PPh₂)₂(L) reacted in CH₂Cl₂ at room temperature to give the mono(alkyne) complexes [WI₂(CO)(L-P,P′)(η²-RC₂R′)] in high yield. The molecular structures of [WI₂(CO)(L-P,P′)(η²-MeC₂R)](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′)(η²-MeC₂Me)]·0.75CH₂Cl₂1 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′)(η²-MeC₂Ph)] 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′)(η²-RC₂R)](R = Me or Ph) as monodentate phosphine ligands with the molybdenum(II) and tungsten(II) complexes [MI₂(CO)₃(NCMe)₂], [MI₂(CO)₃(NCMe)L′](L′= PPh₃, AsPh₃ or SbPh₃), [MoCl(GeCl₃)(CO)₂(NCMe)₂(PPh₃)] and [WI₂(CO)(NCMe)(η²-RC₂R)₂](R = Me or Ph) were found to give a range of bi- and tri-metallic complexes which have all been characterised.