Oxidation addition of H-H bonds to iridium :developing novel active water soluble catalysts for hydrogenation of unsaturates
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The oxidative addition of H-H to iridium(l) trimethylphosphine complexes was studied and the reactivity of the resulting water soluble dihydrido iridium (III) complexes was investigated. One Dihydrido iridium(III) complex, mer-Ir(H)2(PMe3)3CI (2) was characterized by IH, 31p and 13C NMR spectroscopy, CH analysis and single crystal xray diffraction. (2) reacted with the strong sigma donor PMe3 to form [IrH2(PMe3)4]CI (3b) without having to remove the chloride ligand. (2) reacted with monosubstituted acetylenes and an internal diyne in water to form the vinyl complexes Ir(H)(C(R')=C(H)( RÂ»(PMe3)3CI (R = CMe3, C6lis, SiMe3, R' = H, (4)-(6); R' = CCMe3, R= Me, (7Â». (2) also reacted in water with ethynylpyridine to form an unusual metallacycle "trimer" (8). A mechanism for tltrimerizationtl is proposed. (2) also reacted with ethylene in water to form the diethyl iridium complex Ir(CH2CH3)2(PMe3)3CI (8). Encouraged by these results, catalytic hydrogenation of unsaturates in water was investigated. It was found that (2) is active as a water soluble catalyst for hydrogenation of unsaturates. A mechanism for catalytic hydrogenation was proposed.
- Doctoral Dissertations