Reactions of a Ru(II) Phenyl Complex with Substrates that Possess C−N or C−O Multiple Bonds: C−C Bond Formation, N−H Bond Cleavage, and Decarbonylation Reactions

The Ru(II) phenyl complex TpRu(CO)(NCMe)(Ph) ( 1 ) (Tp = hydridotris(pyrazolyl)borate) reacts with carbodiimides to yield amidinate complexes that result from C−C bond formation between the phenyl ligand and the carbodiimide carbon. Complex 1 and N -methylacetamide react to produce benzene and the amidate complex TpRu(CO){( N, O -OC(Me)N(Me)} ( 4 ). The reaction of complex 1 with C⋮N( t Bu) yields TpRu(CO){C⋮N( t Bu)}(Ph) ( 5 ), and heating a solution of PMe 3 and 5 results in the observation of an equilibrium with the product of isonitrile insertion TpRu(CO){C(Ph) N t Bu}(PMe 3 ) ( 6 ) (Δ H = +9(1) kcal/mol and Δ S = +20(3) eu). The reaction of 1 with aromatic aldehydes at elevated temperatures results in C−H activation and decarbonylation of the aldehyde to produce TpRu(CO) 2 (Ar) (Ar = phenyl or p -tolyl) and free benzene. DFT calculations have been incorporated to study coordination and insertion reactions of ethylene, methyleneimine, formaldehyde, HN C NH, and C⋮NH into the Ru−Ph bond of the model fragment (Tab)Ru(CO)(Ph) (Tab = tris(azo)borate). In addition, the energetics of Ru-mediated decarbonylation of formaldehyde have been calculated.