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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 .
Depending on the ligands and the alkene, either Markovnikov or anti-Markovnikov product result. 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.
Ordinarily the reaction is conducted catalytically and usually the substrates are unsaturated organic compounds. Alkenes and alkynes give alkyl and vinyl silanes; aldehydes and ketones give silyl ethers, while esters provide alkyl silyl mixed acetals. Hydrosilylation has been called the "most important application of platinum in homogeneous ...
The insertion of alkenes into metal-hydrogen bonds is a key step in hydrogenation and hydroformylation reactions. The reaction involves the alkene and the hydride ligands combining within the coordination sphere of a catalyst. In hydrogenation, the resulting alkyl ligand combines with a second hydride to give the alkane.
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]
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. Although decarbonylation can be effected by several transition metal complexes, Wilkinson's catalyst has proven the most effective. [1]
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.
[6] [7] His preliminary results showed that acyl halides and aldehydes could be decarbonylated by Pd 0 at high temperatures (200 °C) yielding alkenes; [8] further investigation revealed that stoichiometric quantities of Wilkinson's catalyst was able to affect the same reaction at lower temperatures, [9] now known as the Tsuji-Wilkinson ...