SOLVENT, TEMPERATURE, AND PRESSURE-DEPENDENCE OF THE OXIDATIVE ADDITION OF IODOMETHANE TO COMPLEXES OF THE TYPE RHI(BETA-DIKETONATE)(CO)(PPH3)

A combined solvent-, temperature-, and pressure-dependence study of the oxidative addition of iodomethane to Rh(Sacac)(CO)(PPh3) and Rh(cupf)(CO)(PPh3) was undertaken for a range of solvents covering a large range of epsilon-0 and q(p) values. The kinetic data for the thioacetylacetone (Sacac) complex exhibit no significant dependence on the solvent and are interpreted in terms of a concerted three-center transition state. In the case of the cupferron (cupf) complex, a significant solvent effect was observed for the most polar solvents. This observation is interpreted in terms of a linear transition state and the participation of an ion-pair intermediate at least in the case of the polar solvents. The results are discussed in reference to all the data available in the literature for such reactions.