A new carbyne ligand; synthesis of novel MIV(M = Mo, W) complexes containing terminal halogenomethylidyne ligands: X-ray crystallographic characterisation of η1-chloromethylidyne(dicarbonyl)[tetrakis(1-pyrazolyl)borato]molybdenum(IV)

Abstract

Oxidation of the poly(1-pyrazolyl)borato complexes [M(CO)₃{HB(3,5-Me₂-C₃HN₂)₃}]^–(M = Mo, W) with either [ArN₂]⁺(Ar = aryl) or [Ph₂l]⁺ in the presence of a source of dihalogenoalkyl radicals leads to the formation of the η¹-halogenomethylidyne complexes [Mo(η¹-CX)(CO)₂{HB(3,5-Me₂-C₃HN₂)₃}](X = Cl, Br, and I) and [W(η¹-CCl)(CO)₂{HB(3,5-Me₂-C₃HN₂)₃}]; a closely related complex, {Mo(η¹-CCl)(CO)₂{B(C₃H₃N₂)₄}] has been characterised by X-ray crystallographic methods.