Formation of N, N-Dimethylacrylamide by a Multicenter Hydrocarbamoylation of C2H2 with N, N-Dimethylformamide Activated by Ru5(μ5-C)(CO)15.

Hydrocarbamoylation of C2H2 by N, N-dimethylformamide (DMF) to N, N-dimethylacrylamide was effected by a series of cluster-opening reactions with Ru5(μ5-C)(CO)15 (1). The reaction of 1 with DMF yielded the new complexes Ru5(μ5-C)(CO)14(μ-η2-O═CNMe2)(μ-H) (2) and a minor coproduct Ru5(μ5-C)(CO)13(HNMe2)(μ-η2-O═CNMe2)(μ-H) (3) by a cluster-opening activation of the formyl C-H bond of DMF. Compound 3 was obtained from 2 by a further reaction with DMF. Compound 3 reacted with C2H2 (1 atm, 70 °C) to yield Ru5(μ5-C)(CO)13(μ-η3-O═CNMe2CHCH)(μ-H) (4) by the addition and coupling of C2H2 to the bridging dimethylformamido ligand. Compound 4 contains a σ-π-coordinated, dimethylformamido-substituted vinyl ligand that bridges a Ru-Ru edge of an open Ru5C cluster. The formamido group is also coordinated to one of the metal atoms. The addition of CO (1 atm, 25 °C) to 4 yielded the CO adduct Ru5(μ5-C)(CO)14(η2-O═CNMe2CH═CH)(μ-H) (5) containing a chelating dimethylacrylamido ligand, which released dimethylacrylamide by the reductive elimination of a C-H bond upon a further addition of CO (400 psi, 125 °C) with the re-formation of 1. All of the products were characterized by single-crystal X-ray diffraction analyses.