Chemistry and catalytic properties of ruthenium and osmium complexes. 3. Development of highly active systems for the homogeneous hydrogenation of aldehydes and ketones

Abstract

Acknowledgment. Financial support from CONICIT (Venezuela) and the Fonds der Chemischen Industrie is gratefully acknowledged. We thank V. León and J. Espidel (IVIC) for some NMR measurements, and CEPET for a Graduate Fellowship (to A.A.).

Homogeneous hydrogenation of ketones in the presence of H 2 Ru(CO) 2 (PPh 3 ) 2

“…On the basis of the data obtained and in analogy to those reported in the literature, 3,9,15 a mechanism has been suggested where the rate-determining step is the ketone coordination to the metal-hydrogen bond with formation of a four-centre transition state (Scheme 1). The following step is the ketone insertion into the ruthenium-hydrido bond, with formation of the corresponding alkoxide.…”

“…4,8,9 The catalytically active species involved in this reaction are usually supposed to be hydrido complexes, even if the starting catalyst does not contain hydridic hydrogens.…”

Ruthenium and Osmium

“…Osmium and ruthenium complexes of the type MHX(CO)(PR 3 ) 3 , X = halogen, carboxylate, showed similar, low activity of about TOF 0.5 to 3 h -1 for the hydrogenation of propionaldehyde in toluene at 150 8C, 30 bar H 2 . Acetone was hydrogenated at a slow rate at 150 8C, 65 bar H 2 [121] until the catalyst decomposed to metal, at which point the rate increased and also the solvent, toluene, was hydrogenated [122]. Several other substrates were investigated as described elsewhere [115].…”

Binuclear Complexes of Ruthenium and Osmium Containing Metal Metal Bonds

“…189 This compound has been found to be an effective catalyst for the hydrogenation of propionaldehyde. 190 Sulfur-and selenium-bridged derivatives of type ( 10 H 18 , L = CO) on treatment with HBF 4 followed by addition of NaBH 4 . This compound has a closed structure (Ru-Ru = 0.267 8(1) nm).…”