THE CATALYTIC ACTIVITY OF NEW RUTHENIUM(II) COMPLEXES CONTAINING CHELATING DIPHOSPHINE LIGAND IN THE HOMOGENEOUS HYDROGENATION OF CYCLOHEXENE

A series of new hydridocarbonyl ruthenium(II) complexes containing che lating diphosphine ligands of the type [RuHCl(CO)(PPh3)(L-L)] [L-L = P h2PCH2PPh, 2, Ph2PCH2CH2PPh2 3, Ph2PCH2CH2CH2PPh2 4, cis-Ph2PCH=CHPPh2 5 and Fe(eta5-C5H4PPh2)2 6] has been prepared by the reactions of [Ru HCI(CO)(PPh3)3] 1 with Ph2PCH2PPh2 [dppm, bis(diphenylphosphino)methan e], Ph2PCH2CH2PPh2 [dppe, 1,2-bis(diphenylphosphino)ethane], Ph2PCH2CH 2CH2PPh2 [dppp, 1,3-bis(diphenylphosphino)propanel, cis-Ph2PCH=CHPPh2 [dppv, cis-1,2-bis(diphenylphosphino)ethylene] and Fe(eta5-C5H4PPh2)2 [(dppf, 1, l'-bis(diphenylphosphino)ferrocene] in boiling PhMe. The co mpounds 2-6 are moderately stable in solution. The new compounds were characterized by elemental analysis, IR and H-1 NMR spectroscopy. Comp ounds 1-6 have been shown to catalyse the homogeneous hydrogenation of the C=C bond of cyclohexene; some relations between structures and ca talytic activities are described. The Arrhenius activation energy of c yclohexene for compound 4 is 33.0 kJ mol-1.