Synthesis of Molybdenum and Tungsten Silylimido Complexes. Structure of a Five-Coordinate Bis(silylimido) Complex.

Molybdenum(IV) and tungsten(IV) mono(silylimido) compounds, M(NSiMe 3 )Cl 2 L 3 (M=Mo, L=PMe 3 , M=W, L=PMe 3 , PMePh 2 , have been prepared by the reaction of MCl 2 L 4 with trimethylsilyl azide. When M=W and L=PMePh 2 , the addition of a second equivalent of trimethylsilyl azide produces a tungsten(VI) bis(silylimido) compound, W-(NSiMe 3 ) 2 Cl 2 (PMePh 2 ) (4). X-ray structural determination indicates that 4 possesses a five-coordinate trigonal-bipyramidal structure