[RuCl(η5-C5H5)(PPh3)2] as Catalyst in the Reaction of Primary Amines with Diaryl Diazoalkanes: Unexpected Formation of Imines

The reaction between primary amines (RNH2) and diaryl diazomethanes (Ar2CN2) in the presence of catalytic amounts of the complex [RuCl(eta(5)-(CH5)-H-5)(PPh3)(2)] (1), in chloroform at 60 degreesC, generally affords mixtures of imines Ar2C=NR as main product and amines Ar2CHNHR. Whereas Ar2CHNHR are formed by the expected carbene insertion into the N-H bond of the substrate, the generation of Ar2C=NR is unprecedented. The carbene intermediate [RuCl( CAr2)(eta(5)-C5H5)(PPh3)] seems to be the key-species involved in the formation of both products.