Group 6 metal carbonyl complexes of a family of bulky phosphines: spectroscopic and structural studies of chromium(0)-, molybdenum(0)- and tungsten(0)-pentacarbonylsilylphosphines

The synthesis and spectroscopic data of six Group 6 metal complexes with the silylphosphine ligands, P(C6H5){Si(CH3)3}2 and P(H){Si(CH3)3}2 are reported. The crystal structures of M(P{R}{TMS}2)(CO)5, M = Cr, Mo, W; R = C6H5 and M = Cr; R = H, are reported. All the compounds exhibit the expected structures consisting of an octahedral geometry of five carbonyl ligands and one silylphosphine ligand around the metal center. Analysis of the spectroscopic and structural data, including the previously reported P{Si(CH3)3}3 ligand, indicate the steric bulk of the ligands decreases and the sigma-donating ability increases in the series P{Si(CH3)3}3 < P(C6H5){Si(CH3)3}2 < P(H){Si(CH3)3}2.