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| The structure of Wilkinson's catalyst. |
Wilkinson’s catalyst has the general formula of (R3P)3RhCl. The most representative structure is the phenyl version, (Ph3P)3RhCl. This rhodium complex has been developed to become one of the greatest catalysts for the hydrogenation of carbon-carbon double or triple bonds in a homogeneous phase.
When Kono et. al. has successfully reacted the Wilkinson’s catalyst with catecholborane, via the insertion of the rhodium atom into the B-H bond, in 1975, this provided motivation for the development of the first rhodium-catalyzed hydroboration reaction in 1985.
Wilkinson’s catalyst has also been applied in other catalytic reactions since its first appearance. Wilkinson and his group were probably the first to discover that the conversion of a hydroformylation reaction could be improved by replacing the already well-established cobalt catalyst with a rhodium catalyst. Not only the catalytic activity has increased, the isomeric ratio of the resulting aldehyde products has also improved.
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| A typical hydroformylation reaction. |
As a matter of fact, Wilkinson's catalyst was the original catalyst for the rhodium-catalyzed hydroformylation reaction, until the group has later developed the halide-free HRh(CO)(PPh3)3 complex as the prime hydroformylation catalyst instead.
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| Structure of the (in-situ generated) rhodium catalyst for hydroformylation. |
by Ed Law
Reference:
1. (a) M. A. Bennett, P. A. Longstaff
Complexes of Rhodium(I) with Triphenylphosphine
Chem. Ind. (London ), 1965, 846.
(b) J. A. Osborn, F. H. Jardine, J. F. Young, G. Wilkinson
The Preparation and Properties of Tris(triphenylphosphine)halogenorhodium(I) and Some Reactions Thereof Including Catalytic Homogeneous Hydrogenation of Olefins and Acetylenes and Their Derivatives
J. Chem. Soc. A., 1966, 1711.
(c) J. A. Osborn, G. Wilkinson
Tris(triphenylphosphine)halorhodium(I)
Inorg. Synth. 1967, 10, 67.
2. H. Kono, K. Ito
Oxidative Addition Of 4,4,6-Trimethyl-1,3,2-Dioxaborinane And Benzo[1,3,2]Dioxaborole To Tris (Triphenylphosphine)Halogenorhodium".
Chem. Lett., 1975, 1095.
3. D. Männing, H. Nöth (1985).
Catalytic Hydroboration with Rhodium Complexes
Angew. Chem. Int. Ed., 1985, 24, 878.
4. D. Evans, J. A. Osborn, G. Wilkinson
Hydroformylation of Alkenes by Use of Rhodium Complex Catalyst
J. Chem. Soc., 1968, 33, 3133.
