Synthesis and spectroscopic properties of Mo(VI) complexes with phosphine oxide ligands and the crystal structures of [MoO 2X 2(OPMe 3) 2] (X=Cl or Br) and [MoO 2Br 2{ o-C 6H 4(P(O)Ph 2) 2}] · 2CH 2Cl 2

Abstract

The colourless neutral Mo(VI) complexes [MoO 2Cl 2(OPMe 3) 2], [MoO 2Cl 2(L–L)] (L–L=Ph 2P(O)CH 2P(O)Ph 2, Ph 2P(O)CH 2CH 2P(O)Ph 2 and o-C 6H 4(P(O)Ph 2) 2) have been obtained in good yield by reaction of MoO 2Cl 2 with the ligand in anhydrous CH 2Cl 2 solution. The corresponding light yellow bromo species were obtained from reaction of a CH 2Cl 2 solution of the phosphine oxide ligand with MoO 3 and HBr. The complexes have been characterised by IR, 1H, 31P{ 1H} and where possible by 95Mo NMR spectroscopy and trends in the spectroscopic data are discussed. Crystal structures of [MoO 2X 2(OPMe 3) 2] (X=Cl or Br) and [MoO 2Br 2{ o-C 6H 4(P(O)Ph 2) 2}] · 2CH 2Cl 2 are also described. Each of the compounds adopts a distorted octahedral geometry at Mo(VI) with trans halo ligands, a cis dioxo unit and with the O-bound phosphine oxide ligands completing the coordination environment.