REACTIVITY OF MH(ETA-2-H2BH2)(CO)(PIPR3)2 (M = OS, RU) TOWARD ELECTROPHILES - SYNTHESIS OF NEW HYDRIDOCARBONYLOSMIUM(II) AND RUTHENIUM(II) COMPLEXES CONTAINING TRIISOPROPYLPHOSPHINE AS LIGAND

The complexes [(PiPr3)2(CO)HM(mu,eta4-BH4)MH(CO)(PiPr3)2]BF4 (5, 6), MH(eta2-O2CR*)(CO)(PiPr3)2 (7-13) and MH(pz)(CO)(Hpz)(PiPr3)2 (14,15) (M = Os, Ru) have been prepared by reaction of MH(eta2-H2BH2)(CO)-(PiPr3)2 (M = Os, Ru) with HBF4, R*CO2H (R* = (S)-CH(NaphOMe)Me, (R)-CH(OMe)Ph, (R)-C(CF3) (OMe)Ph, (S)-CHOC(=O)CH2CH2) and Hpz (pyrazole), respectively. 5 and 6 react with molecular hydrogen, tetrafluorobenzobarrelene(TFB),methyl vinyl ketone,acetonitrile,and acetone to give[OsH(eta2-H2)(CO)(PiPr3)2]+ (16),[OsH(eta2-H2)(CO)(OH2)(PiPr3)2]+(17),[OsH(CO)(TFB)(PiPr3)2]+(18),[OsH(CO)(pi-CH2=CHC(=O)-CH3)(PiPr3)2]+ (19), [MH(CO)(CH3CN)2(PiPr3)2]+ (M = Os (20), Ru (21)) and [RuH(CO)(eta1-(CH3)2CO)2-(PiPr3)2]+ (22). In solution 22 dissociates an acetone molecule to give [RuH(CO)(eta1-(CH3)2CO)(PiPr3)2]+ (23). The cations [MH(CO)(HpZ)2(PiPr3)2]+ (M = Os (24), Ru (25)) were obtained by addition of HBF4 to diethyl ether solutions of 14 and 15. The latter react with HCI to give a mixture of two isomers of MHCl(CO)(Hpz)(PiPr3)2 (M = Os (26), Ru (27)). The catalytic activity of 7-13 in asymmetric hydrogen transfer from 2-propanol to acetophenone is also described. The osmium carboxylates lead to considerably higher optical yields than ruthenium complexes.