Synthesis and structural characterisation of [Mo(NNPh 2)(NPh 2)(mesityl) 2(OC 6F 5)] and {[W(NNPh 2)(NPh 2)(OSiMe 3)] 2(μ-Cl) 2(μ-O)}: isodiazene complexes with bulky amide groups arising via NN bond cleavage

Abstract

Reaction of [Mo(NNPh 2)Cl 3] with mesitylMgCl (mesityl=2,4,6-Me 3C 6H 2) followed by addition of pentafluorophenol affords the bis(alkylated) complex [Mo(NNPh 2)(NPh 2)(mesityl) 2(OC 6F 5)] ( 1) in poor yield (20–30%). In the case of [WO 2Cl 2(dme)], reaction with Ph 2NNH 2·HCl in refluxing triethylamine/trimethylsilylchloride affords the binuclear complex {[W(NNPh 2)(NPh 2)(OSiMe 3)] 2(μ-Cl) 2(μ-O)} ( 2) in good yield (approximately 75%). The crystal structures of 1 and 2 have been determined. In 1, the trigonal-bipyramidal Mo atom is coordinated by an axial linear isodiazene group trans to a pentafluorophenoxide ligand, whilst equatorial positions are occupied by two mesityl groups and an amide (NPh 2) group. For 2, the molecule is best described as possessing a triply bridging (2x μ-Cl, μ-O) confacial bioctahedral geometry, with the longer bridging bonds trans to the isodiazene group The amide groups (NPh 2) in each structure must arise through NN bond cleavage.