Phenylimido complexes of tungsten(VI) and tungsten(V). The crystal and molecular structure of Trichloro(phenylimido)bis(trimethylphosphine)tungsten(V)

Abstract

Tetrachloro(phenylimido)tungsten(VI) is reduced by trimethylphosphine in tetrahydrofuran solution to give the tungsten(V) complex PhNWCl₃(Pme₃)₂ in which the phenylimido multiple bond remains intact. The complex reacts with oxygen to form the phosphine oxide complex PhNWCl₃ (OPMe₃)₂. Pyridine and alkyl cyanides do not reduce tetrachloro(phenylimido)tungsten(V1) but give the adducts PhNWCl₄.L (L = py, MeCN, EtCN). The crystal and molecular structure of the title complex has been determined from single-crystal X-ray diffractometer data. The crystals are monoclinic with a 14.903, b 10.221, c 14.380Å  β 116.05º, space group P2₁/c, Z 4. The structure has been solved by Patterson and Fourier methods and refined to R 0.030 for the 1566 observed data. Distorted octahedral coordination geometry is found with two trans trimethylphosphine and two trans chloride ligands; a third chloride is trans to the phenylimido group. The W-N(imido) bond length is 1.731 Å.