Daniel K. W. Wang

Catalytic asymmetric hydrogenation using ruthenium(II) chiral phosphine complexes

The ruthenium(II) complexes [Ru2X4{(+)(diop)}3][ X = Cl, Br; diop = 2,2-dimethyl-1,3-dioxolan-4,5-bis(methylene)bis(diphenylphosphine)], which contain a bridging bridentate phosphine ligand, catalyse under mild conditions the hydrogenation of unsaturated carboxylic acids and can give products of high optical yields (ca. 60%).

X-Ray crystal structure of trans-chlorohydridobis(diop)ruthenium(II); an octahedral complex with inequivalent phosphorus atoms

The HRuCl(diop)2 complex, although showing 31P and high-field 1H n.m.r. spectra typical of a cis-structure with inequivalent phosphorus atoms, has been shown by X-ray crystallography to have a distorted octahedron structure with the hydrogen trans to chlorine.

Stoicheiometric hydrogenation of olefins using HRuCl(PPh3)3 and formation of an ortho-metallated ruthenium(II) complex

Stoicheiometric hydrogenation of olefins using HRuCl(PPh3)3 in the absence of hydrogen results in formation of the dimer [(Ph3P)ClRu(o-C6H4PPh2)]2; this complex reacts with H2, and HCl, to yield in solution the catalytically important bisphosphine complexes RuXCl(PPh3)2(X = H, Cl).

Base-promoted reactions of dihydrogen with ruthenium(III) tertiary-phosphine and -arsine complexes

Reaction of H2 with the ruthenium(III) complexes RuX3L2(X Cl or Br; L = PPh3 or Asph3) can yield the five-co-ordinate dimeric ruthenium(II) hydride complexes [HRuXL2]2; the reactions proceed generally via intermediate HRu2L2 and RuX2L2 speices, and evidence is presented for the existence of [HRuBr2-(AsPh3)2], the first reported ruthenium(III) hydride.

Activation of Saturated Hydrocarbons by Ruthenium (I) Complexes

Some studies on the activation of dihydrogen by ruthenium(III) complexes of the type RuX3L2 (X = halide, L = tertiary-phosphine or -arsine ligand) led us to the synthesis of the hydridoruthenium(II) complexes [HRuXL2]2, which were well-characterized by elemental analysis, molecular weight data, i.r., and 1H and 31P n.m.r.1,2 In attempts to substantiate any role for such bisphosphine species in homogeneous hydrogenations catalyzed by the trisphosphine system3 HRuCl(PPh3)3, we decided to study such processes using the isolated hydridobisphosphine dimer. Some unexpected and novel kinetics reported here suggest the involvement of ruthenium(I) species, and a reverse step detected in the hydrogenation mechanism indicates cleavage of a C-H bond in the saturated hydrocarbon moiety by such species. A brief communication on this work has appeared.2

Catalysis by chlorohydridobis(triphenylphosphine)ruthenium(II) species. Novel kinetics and their implications for activation of saturated hydrocarbons

Novel kinetics for hydrogenation of acrylamide catalysed by [{HRuCl(PPh3)2}2] in solution indicate a mechanism which includes competitive oxidative addition reactions of H2 and propionamide (C–H cleavage) to ruthenium(I) centres.