Highly Selective Hydrogenation of Carbon–Carbon Multiple Bonds Catalyzed by the Cation [(C₆Me₆)₂Ru₂(PPh₂)H₂]⁺: Molecular Structure of [(C₆Me₆)₂Ru₂(PPh₂)(CHCHPh)H]⁺, a Possible Intermediate in the Case of Phenylacetylene Hydrogenation

Abstract

The dinuclear cation [(C6Me6)2Ru2(PPh2)H2]+ (1) has been studied as the catalyst for the hydrogenation of carbon–carbon double and triple bonds. In particular, [1][BF4] turned out to be a highly selective hydrogenation catalyst for olefin functions in molecules also containing reducible carbonyl functions, such as acrolein, carvone, and methyljasmonate. The hypothesis of molecular catalysis by dinuclear ruthenium complexes is supported by catalyst‐poisoning experiments, the absence of an induction period in the kinetics of cyclohexene hydrogenation, and the isolation and single‐crystal X‐ray structure analysis of the tetrafluoroborate salt of the cation [(C6Me6)2Ru2(PPh2)(CHCHPh)H]+ (2), which can be considered as an intermediate in the case of phenylacetylene hydrogenation. On the basis of these findings, a catalytic cycle is proposed which implies that substrate hydrogenation takes place at the intact diruthenium backbone, with the two ruthenium atoms acting cooperatively in the hydrogen‐transfer process.

Dinuclear Ruthenium and Osmium Arene Trihydrido Complexes: Versatile Water-Soluble Synthons in Organometallic Chemistry

“…On the other hand, the phosphido derivative [(η 6 -C 6 Me 6 ) 2 Ru 2 (μ 2 -PPh 2 )(μ 2 -H) 2 ] + , which selectively catalyzes the hydrogenation of carbon−carbon double and triple bonds without catalyzing the attack on other reducible functions, seems to operate as a molecular catalyst, at least under these mild conditions (60 °C and 50 bar of H 2 ) . The cluster cation [(η 6 -C 6 Me 6 ) 2 Ru 2 (μ 2 -PPh 2 )(μ 2 -η 1 :η 2 -CHCHPh)(μ 2 -H)] + , isolated as the tetrafluoroborate salt from the catalytic hydrogenation of phenylacetylene, suggests a reaction course involving initial insertion of the unsaturated substrate into one of the three hydrido bridges of [(η 6 -C 6 Me 6 ) 2 Ru 2 (μ 2 -PPh 2 )(μ 2 -H) 2 ] + , followed by the transfer of a second one onto the ligand formed; a tentative catalytic cycle is outlined in Scheme .…”

Facile synthesis of biomass-based carbon materials nano-Ni-based catalysts and its application in selective hydrogenation of alkynes

“…In the process of developing low cost, high activity, and high selectivity catalysts for selective hydrogenation of benzene acetylene 12 . How to combine high activity and selectivity of catalysts has been a major challenge in this field.…”