Homogeneous hydrogenation and isomerisation of alkenes by means of μ‐dichloro(π‐benzene)ruthenium(II)

Prolonged treatment of μ‐dichloro(π‐benzene)ruthenium(II) with hydrogen in dimethylformamide solution results in the formation of a catalyst allowing of a rapid and homogeneous hydrogenation of compounds containing alkenic bonds. The hydrogenation rates of 1‐alkenes, cycloalkenes, and alkenes containing functional groups have been studied quantitatively. The kinetics of the hydrogenation of cyclooctene can be described by the rate expression: R=A[Ru] [H2][S]/(B + C[S]) where A, B and C are constants and [Ru], [H2] and [S] the catalyst, hydrogen and alkene concentration, respectively. From the hydrogenation data obtained for cyclooctene, the activation energy was calculated to be ca 6 kcal. mole−1. The results of experiments involving isotopic exchange with molecular hydrogen‐deuterium gas mixtures and the incorporation of deuterium during the deuterogenation of cyclooctene suggest that the actual active catalytic species is (π‐benzene)Ru‐H.