Reactions of MH(OTf)(NBD)(PPh3)2 (M = Ru, Os) with H2
journal contributionposted on 2000-09-27, 00:00 authored by Shu Tak Lo, Zhitao Xu, Ting Bin Wen, Weng Sang Ng, Sheng Hua Liu, Zhong Yuan Zhou, Zhenyang Lin, Chak Po Lau, Guochen Jia
Treatment of RuHCl(NBD)(PPh3)2 (NBD = norbornadiene) with AgOTf produced RuH(OTf)(NBD)(PPh3)2. Reaction of RuH(OTf)(NBD)(PPh3)2 with H2 in benzene gave norbornene and [(η6-C6H6)RuH(PPh3)2]OTf. The same reaction in CD2Cl2 in the presence of added PPh3 produced norbornane and [RuH(PPh3)4]OTf. Reaction of OsH3Cl(PPh3)3 with norbornadiene produced OsHCl(NBD)(PPh3)2, which was converted to OsH(OTf)(NBD)(PPh3)2 on treatment with AgOTf. Reaction of OsH(OTf)(NBD)(PPh3)2 with H2 in benzene gave norbornane and [(η6-C6H6)OsH(PPh3)2]OTf. In dichloromethane, OsH(OTf)(NBD)(PPh3)2 reacted with H2 in the presence of added PPh3 to produce norbornane and [OsH3(PPh3)4]OTf. Supported by computational studies, it is assumed that the dihydrogen complexes [MH(H2)(NBD)(PPh3)2]+ (M = Ru, Os) were involved in the hydrogenation reactions. Two reaction pathways for the conversion of [RuH(H2)(NBD)(PH3)2]+ to [RuH(NBE)(PH3)2]+ (NBE = norbornene) have been studied by density functional theory calculations. The results show that the first hydrogen transferred to the olefin ligand is more likely from the hydride ligand rather than from the dihydrogen ligand.