Evidence for Ambiphilic Behavior in (CO)₅W=NPh. Conversion of Carbonyl Compounds to N-Phenyl Imines via Metathesis

(CO)₅W=NPh (5) has been generated in the presence of aldehydes, ketones, and thioketones and found to undergo metathesis with these substrates to yield N-phenyl imines. The participation of complex 5 as a nucleophile in these reactions and the previously reported reaction of 5 with PPh₃ confirm the ambiphilic nature of (CO)₅W=NPh. This is consistent with the electronic structure of the model compound (CO)₅W=NMe, as obtained from extended Hückel calculations. The heteroatom-substituted nitrene complex (CO)₅W=NNMe₂ (7) is less electrophilic but still functions as a nucleophile in its reaction with PhCHO to give Me₂NN=CHPh.