Reactivity of MH(.eta.2-H2BH2)(CO)(PiPr3)2 (M = osmium, ruthenium) toward electrophiles: synthesis of new hydridocarbonylosmium(II) and -ruthenium(II) complexes containing triisopropylphosphine as ligand

The complexes [(PiPr3)2(CO)HM(M,t;4-BH4)MH(CO)(PzPr3)2]BF4 (5, 6), MH(y-02CR*)(CO)(PiPr3)2 (7-13) MH(pz)(CO)(Hpz)(P/Pr3)2 (14,15) (M = Os, Ru) have been prepared by reaction of MH(t/-H2BH2)(CO)- (Pz'Pr3)2 (M = Os, Ru) with HBF4, R*C02H (R* = (S)-CH(NaphOMe)Me, (R)-CH(OMe)Ph, (R)-C(CF3) -1(OMe)Ph, (S)-CH0C(=0)CH2CH2) and Hpz (pyrazole), respectively. 5 and 6 react with molecular hydrogen, (TFB), methyl vinyl ketone, acetonitrile, and acetone to give [OsH(r/-H2)(CO)(Pz'Pr3)2]+(16), [OsH(tj2-H2) (CO)(OH2)(Pt'Pr3)2]+ (17), [OsH(CO)(TFB)(PzPr3)2]+ (18), [OsH(CO)(tt-CH2=CHC(=0)-CH3)(Pz'Pr3)2]+ (19), [MH(CO)(CH3CN)2(PzPr3)2]+ (M = Os (20), Ru (21)) and [RuH(CO)(„1-(CH3)2CO)2-(PiPr3)2]+ (22). In solution 22 dissociates an acetone molecule to give [RuH(CO)(r;l-(CH3)2CO)(PzPr3)2]+ (23). The cations [MH(CO)(Hpz)2(Pz'Pr3)2]+ (M = Os (24), Ru (25)) were obtained by addition of HBF4 to diethyl ether solutions of 14 and 15. The latter react with HC1 to give a mixture of two isomers of MHCl(CO)(Hpz)(Pz'Pr3)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.