383905-99-5Relevant articles and documents
Nmr studies of Ru3(CO)10(PMe2Ph)2 and Ru3(CO)10(PPh3)2 and their H2 addition products: Detection of new isomers with complex dynamic behavior
Blazina,Duckett,Dyson,Johnson,Lohman,Sleigh
, p. 9760 - 9768 (2001)
The clusters Ru3(CO)10L2, where L = PMe2Ph or PPh3, are shown by NMR spectroscopy to exist in solution in at least three isomeric forms, one with both phosphines in the equatorial plane on the same ruthenium center and the others with phosphines in the equatorial plane on different ruthenium centers. Isomer interconversion for Ru3(CO)10(PMe2Ph)2 is highly solvent dependent, with ΔH? decreasing and ΔS? becoming more negative as the polarity of the solvent increases. The stabilities of the isomers and their rates of interconversion depend on the phosphine ligand. A mechanism that accounts for isomer interchange involving Ru - Ru bond heterolysis is suggested. The products of the reaction of Ru3(CO)10L2 with hydrogen have been monitored by NMR spectroscopy via normal and para hydrogen-enhanced methods. Two hydrogen addition products are observed with each containing one bridging and one terminal hydride ligand. EXSY spectroscopy reveals that both intra- and interisomer hydride exchange occurs on the NMR time scale. On the basis of the evidence available, mechanisms for hydride interchange involving Ru - Ru bond heterolysis and CO loss are proposed.
Direct comparison of hydrogenation catalysis by intact versus fragmented triruthenium clusters
Blazina, Damir,Duckett, Simon B.,Dyson, Paul J.,Lohman, Joost A. B.
, p. 3874 - 3877 (2001)
The solvent plays a pivotal role in controlling the selectivity of the catalytic hydrogenation of alkenes and alkynes by [Ru3(CO)12-x(PPh3)x] (x = 1 or 2) with the mechanism varying with the solvent polarity. In polar solvents the reaction proceeds via H2 addition products based on [Ru3(H)(μ-H)(CO)9(PPh3)2], as demonstrated by parahydrogen-induced polarization (PHIP). In nonpolar solvents catalysis by [RuH2(CO)2(PPh3)(substrate)], resulting from fragmentation, competes with that by the intact cluster.
