CRYSTAL AND MOLECULAR-STRUCTURE OF AN ASYMMETRIC HYDROGENATION CATALYST SUBSTRATE ADDUCT, DELTA-BIS(TIGLATO)((R)-2,2'-BIS(DIPHENYLPHOSPHINO)-1,1'-BINAPHTHYL)-RUTHENIUM(II), [RUII(BINAP)(O2CCME=CHME)2]

The molecular structure of an active catalyst in the homogeneous asymmetric hydrogenation of tiglic acid has been determined by single-crystal X-ray crystallography. Bis(tiglato){(R)-2,2'-bis(diphenyl-phosphino)-1,1'-binaphthyl}ruthenium(II), (R)-1b, crystallizes in the monoclinic space group P2(1) with Z = 2, a = 12.709 (5) angstrom, b = 15.622 (5) angstrom, c = 11.289 (5) angstrom, beta = 99.43 (4)degrees, R = 0.021, and R(w) = 0.027. The tiglate ligands are eta-2-carboxylate-bound. The configuration at the metal is DELTA, and the conformation of the seven-membered chelate ring is lambda. No bonding interactions between the C=C bonds of the substrates and the metal center are found in the solid state. The coordination environment of the Ru atom in 1b in the solid state is essentially the same as that in noncoordinating solvents, as deduced by NMR spectroscopy. These results are consistent with the conclusion, on the basis of kinetic measurements previously reported, that if coordination of the C=C bond to Ru is a prerequisite to insertion into a Ru-H bond, then such coordination must occur after reaction with H2.