Ruthenium(II)-Mediated Carbon−Carbon Bond Formation between Acetonitrile and Pyrrole: Combined Experimental and Computational Study

The reaction of TpRu(CO)(NCMe)(Me) ( 1 ) and pyrrole forms TpRu(CO){κ 2 - N,N -(H)N C(Me)(NC 4 H 3 )} ( 2 ). The formation of complex 2 involves the cleavage of the N−H bond and 2-position C−H bonds of pyrrole as well as a C−C bond forming step between pyrrole and the acetonitrile ligand of 1 . Mechanistic studies indicate that the most likely reaction pathway involves initial metal-mediated N−H activation of pyrrole to produce TpRu(CO)( N -pyrrolyl)(NCMe) ( 3 ) followed by C−C bond formation and proton transfer. Complex 3 has been independently prepared and demonstrated to convert to 2 . Computational studies support the suggested selectivity for initial N−H bond cleavage in preference to C−H bond activation.