Reactivity of the Amido Complex [Re(NHpTol)(CO)3(bipy)] toward Neutral Organic Electrophiles

The amido complex [Re(NHpTol)(CO)3(bipy)] (1) reacts with pTolNCS and with Ph2CCO giving the products of the insertion of these heterocumulenes into the Re−N and N−H bonds, the complexes [Re{SC(NpTol)(NHpTol)}(CO)3(bipy)] (2) and [Re{N(pTol)C(O)CHPh2}(CO)3(bipy)] (3), respectively. The reaction of 1 with activated acetylenes containing at least one alkoxycarbonyl group afforded the compounds [Re{N(pTol)C(R‘)C(R)C(OH)}(CO)3(bipy)] (4ac). The formation of the metallacycle present in these compounds involves the activation of one of the carbonyl ligands of 1. The structures of the complexes 2, 3, and 4b have been determined by single-crystal X-ray diffraction. 13C NMR and crystallographic data indicate that the metal-bonded carbon atom of the metallacycle possesses carbene character.