The kinetics of base hydrolysis of chloropentakis(alkylamine)rhodium(III) ions

Abstract

The kinetics of the base hydrolysis of the complex ions [Rh(NH₂R)₅Cl]²⁺(R = Me, Et, or Prⁿ) have been studied and values of the rate constants and activation parameters determined. For all the complexes the observed first-order rate constants were found to be proportional to the hydroxide ion concentration and to increase as the size of the amine, RNH₂, increased. The increase in the rate constant was found to arise from a small but steady decrease in the activation enthalpy for the complexes and this is thought to be consistent with a S_N1 (c.b.) mechanism (c.b. = conjugate base) where steric effects alone are the most important factor in controlling the difference in the rates of these reactions.