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Wilkinson's catalyst (chloridotris(triphenylphosphine)rhodium(I)) is a coordination complex of rhodium with the formula [RhCl(PPh 3) 3], where 'Ph' denotes a phenyl group. It is a red-brown colored solid that is soluble in hydrocarbon solvents such as benzene, and more so in tetrahydrofuran or chlorinated solvents such as dichloromethane .
The Tsuji–Wilkinson decarbonylation reaction is a method for the decarbonylation of aldehydes and some acyl chlorides. The reaction name recognizes Jirō Tsuji, whose team first reported the use of Wilkinson's catalyst (RhCl(PPh 3) 3) for these reactions: RC(O)X + RhCl(PPh 3) 3 → RX + RhCl(CO)(PPh 3) 2 + PPh 3
Wilkinson's catalyst, RhCl(PPh 3) 3 is a square planar Rh(I) complex of historical significance used to catalyze the hydrogenation of alkenes. Vaska's complex , trans -IrCl(CO)(PPh 3 ) 2 , is also historically significant; it was used to establish the scope of oxidative addition reactions.
The difference in regioselectivity is more pronounced in the hydroboration of vinylarenes with HBcat. Wilkinson's catalyst or the cation Rh(COD) 2 (in the presence of PPh 3) produces the Markovnikov product. [12] [13] The anti-Markovnikov product is produced in the absence of a catalyst. [14]
Mechanism for the hydrogenation of a terminal alkene using Wilkinson's catalyst. Homogeneous catalysts are also used in asymmetric synthesis by the hydrogenation of prochiral substrates. An early demonstration of this approach was the Rh-catalyzed hydrogenation of enamides as precursors to the drug L-DOPA. [10]
31 P-NMR spectrum of Wilkinson's catalyst (RhCl(PPh 3) 3) in toluene solution. In addition to 31 P– 31 P coupling between the two types of phosphine centers, 103 Rh– 31 P coupling is also evident. The chemical shifts are referenced to external 85% H 3 PO 4.
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Karstedt's catalyst was later introduced. It is a lipophilic complex that is soluble in the organic substrates of industrial interest. [10] Complexes and compounds that catalyze hydrogenation are often effective catalysts for hydrosilylation, e.g. Wilkinson's catalyst.