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π-allylic complexes or rhodium(III) and platinum(II) III. Chemical reactivity of π-allylic rhodium(III) complexes

1968; Elsevier BV; Volume: 13; Issue: 2 Linguagem: Inglês

10.1016/s0022-328x(00)82776-x

1872-8561

H. C. Volger, Kees Vrieze,

Synthetic Organic Chemistry Methods

The reactions of L2Rh(π-C3H4R)Cl2 [L = (C6H5)3P, (C6H5)3As or (C6H5)3Sb and R = H or CH3] with sulfur dioxide, ethene and carbon monoxide were studied. Sulfur dioxide gives rise to the formation of a σ-allylic rhodium-sulfur dioxide complex. With carbon monoxide L2Rh(π-C3H4R)Cl2 (L = triphenylphosphine or arsine) produces L2(CO)RhCl and (methyl)allyl chloride in quantitative yields. The reaction proceeds via a number of intermediates (trivalent rhodium π- and σ-allyl and insertion products). Ethylene dimerizes into a mixture of butenes; the catalytic activity of the complex is rather poor. The ease of displacement of the ligand by either ethylene or carbon monoxide decreases in the order (C6H5)3As > Cl # (C6H5)3P. No specific correlation has been found between the destabilizing influence of the ligand L on the metal-π-methallyl bond and the rate of the reaction with carbon monoxide.