American Chemical Society
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Ruthenium(II) Complexes Containing Bis(2-(diphenylphosphino)phenyl) Ether and Their Catalytic Activity in Hydrogenation Reactions

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posted on 2007-02-05, 00:00 authored by Ramalingam Venkateswaran, Joel T. Mague, Maravanji S. Balakrishna
The half-sandwich complexes [(η5-C5H5)RuCl(DPEphos)] (1) and [{(η6-p-cymene)RuCl2}2(μ-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 [(η6-p-cymene)RuCl2]2, respectively. Treatment of DPEphos with cis-[RuCl2(dmso)4] afforded fac-[RuCl23-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)(μ-4,4‘-bipyridine)]n (6), and mer,trans-[RuCl23-P,P,O-DPEphos)(PPh3)] (7), respectively. Refluxing [(η6-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 15, 7, and 8 are confirmed by X-ray crystallography. The catalytic activity of these complexes for the hydrogenation of styrene is studied.