Crabtree’s catalyst hydrogenation

Iridium complexes such as IrCl(COD)(L-L), [Ir(COD)(L-L)]+ and [Ir(COD)-(py)(PR3)2]+ are active catalysts for the hydrogenation of a variety of substrates, particularly tetrasubstituted alkenes, e.g. [Ir(COD)(py)(PCy3)] known as Crabtree s catalyst, hydrogenates tetramethylethylene. On the other hand, [Ir(COD)(py)2]+ is inactive, apparently since it does not add H2. The hydrido cation [Ir(H)2(COD)(i72-Pr,2PCH2CH2OMe)]+, with a chelating P—O ligand, selectively hydrogenates phenylacetylene to styrene, via Ir—CH=CHPh intermediates.2... 

Hi, Crabtree s catalyst Hydrogen, l,S Cyclooctadiene)(pyridine (tricvclohexvlphosphlne irldium(l) heKaruoroohosohate 1333-74-0 64S36 73-3 7 6 6.8 Flammable. Relative cost of iridium very expensive. Catalyst can be recycled. 

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