Ruthenium(II) complexes containing bis(2-(diphenylphosphino)phenyl) ether and their catalytic activity in hydrogenation reactions

Abstract

The half-sandwich complexes [(eta(5)-C5H5)RuCl(DPEphos)] (1) and [{(eta(6)-p-cymene)RuCl2}(2)(mu-DPEphos)] (2) were synthesized by the reaction of bis(2-(diphenylphosphino)phenyl) ether (DPEphos) with a mixture of ruthenium trichloride trihydrate and cyclopentadiene and with [(eta(6)-p-cymene)RuCl2](2), respectively. Treatment of DPEphos with cis-[RuCl2(dmso)(4)] afforded fac-[RuCl2(kappa(3)-P,O,P-DPEphos)(dmso)] (3). The dmso ligand in 3 can be substituted by pyridine, 2,2'-bipyridine, 4,4'-bipyridine, and PPh3 to yield trans,cis-[RuCl2(DPEphos)(C5H5N)(2)] (4), cis,cis-[RuCl2(DPEphos)(2,2'-bipyridine)] (5), trans,cis-[RuCl2(DPEphos)(mu-4,4'-bipyridine)](n) (6), and mer,trans-[RuCl2(kappa(3)-P,P,O-DPEphos)(PPh3)] (7), respectively. Refluxing [(eta(6)-p-cymene)RuCl2](2) with DPEphos in moist acetonitrile leads to the elimination of the p-cymene group and the formation of the octahedral complex cis,cis-[RuCl2(DPEphos)(H2O)(CH3CN)] (8). The structures of the complexes 1-5, 7, and 8 are confirmed by X-ray crystallography. The catalytic activity of these complexes for the hydrogenation of styrene is studied.