802902-84-7Relevant academic research and scientific papers
Synthesis, molecular structure and catalytic activity of six-coordinate chloro(hydrido)- and dihydridoruthenium(II) and -osmium(II) complexes with the chiral ligands PiPr2NH(Me)Ph, (S,S)-Chiraphos and (S,S,)-Diop
Schluenken, Christoph,Esteruelas, Miguel A.,Lahoz, Fernando J.,Oro, Luis A.,Werner, Helmut
, p. 2477 - 2487 (2004)
The five-coordinate compounds [MHCl(CO)(Pir3)2] (where 1a: M = Ru; 1b: M = Os) react with PiPr2R* [where R* = CH(Me)Ph] to give the octahedral complexes mer-[MHCl(CO)(PiPr 2R*)3] (6 and 7). The lability of the phosphane trans to the hydride is illustrated by the replacement reactions with CO, P(OMe)3 and C2(CO2Me)2, which afford the substitution products [MHCl(CO)(L)(PiPr2R*)2] (8-12) in high yields. The reactions of 1a and 1b with (S,S)-Chiraphos and (S,S)-Diop lead to one or two diastereoisomers of the chelate complexes [MHCl(CO)(PiPr3)(Chiraphos)] (15, 16) and [MHCl(CO)(PiPr 3)(Diop)] (17, 18); the ratio of the diastereoisomers is dependent on the metal, the bidentate ligand and the reaction conditions. The racemate of [OsHCl(CO)(PiPr3)(dppe) (14) was obtained from lb and 1,2-C 2H4(PPh2)2 (dppe). The hydrido(tetrahydroboranato) compounds [MH(κ2-H 2BH2)(CO)(PiPr3)2] (where 2a: M = Ru; 2b: M = Os) also react with (S,S)-Chiraphos and (S,S)-Diop to give either the mononuclear, octahedral, chelate complexes 19-21 or, for M = Os and (S,S)-Diop, the dinuclear compound [{OsH2(CO)(PiPr3) 2}2(μ-Dop)] (22). The molecular structure of 22 was determined crystallographically. Treatment of [OsH2Cl 2(PiPr3)2] (23) with two equivalents of (S,S)-Chiraphos afforded stepwise [OsH2Cl2(PiPr 3)(Chiraphos)] (25) and, after reductive elimination of HCl and displacement of P/Pr3, trans-[OsHCl(Chiraphos)2] (24). Both 24 and [OsH2-(Chiraphos)2] (27), which was prepared from 2,1 and NaBH4/ MeOH, were transformed with HBF4 in diethyl ether into the dihydrogen complexes [OsCl(H2)(Chiraphos) 2]BF4 (28) and [OsH(H2)(Chiraphos) 2]BF4 (29) in excellent yields. The catalytic activity of the chloro(hydrido)- and dihydridometal derivatives in the asymmetric transfer hydrogenation of acetophenone with 2-propanol was investigated. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
