Electrophilic benzylidene(pentacarbonyl)-chromium(0) and -tungsten(0) complexes: isolation, characterization, and an unusual thermolytic reaction of the tungsten compounds

Abstract

The reaction of the anionic alkyl complexes of chromium and tungsten, NEt₄ ⁺[(CO)₅M{CH(OMe)(p-C₆H₄R)}]^–(M = Cr, R = OMe; M = W, R = OMe, Me, H) with HBF₄·Et₂O yields isolable, strongly electrophilic benzylidene(pentacarbonyl) complexes, (CO)₅MCH(p-C₆H₄R); thermolysis of the tungsten compounds gives µ-benzylidenebis(pentacarbonyltungsten) complexes, [(CO)₅W]₂[µ-CH(p-C₆H₄R)].