OXIDATIVE ADDITION OF MERCURY(II)CYANIDE TO BETA-DIKETONATOBIS-(TRIPHENYLPHOSPHITE)RHODIUM(I) COMPLEXES

The kinetics of the oxidative addition of Hg(CN)2 to [Rh(β-diketone)(P(OPh)3)2] in acetone medium were studied. Various β-diketones, with different electronic and steric properties, were used to determine their effect on the rate of the oxidative addition reactions. The structure of the product of the oxidative addition was proposed with the aid of i.r.,1H-,13C- and31P n.m.r. spectra. A product in which cis addition took place with the CN- and one P(OPh)3 group in the axial positions of an octahedron were proposed. A second order rate law, electronic and steric factors influencing the reaction rate as well as large negative values for the entropy of activation, supported an associative type of mechanism, which probably proceeds via a cyclic three-centred transition state. © 1990 Chapman and Hall Ltd.