Micellar Effects on a Ligand Substitution Reaction: Kinetics of the Formation of[Fe(CN)_5(mupz)Ru(NH_3)_5], from [Fe(CN)_5H_2O]~(3-) and[Ru(NH_3)_5pz]2+, in the Presence of Anionic Micelles

摘要

The kinetics of substitution of H_2O by Ru(NH_3)_5pz~(2+)(pz = pyrazine)in Fe(CN)_5H_2O~(3-)have been studied in micellar aqueous solutions of sodium dodecylsulfate(SDS).Experimental results are discussed by using an approach based on the transition-state theory.This approach is better than others based on the pseudophase model,which can alsobe used,because it is able to give a clear meaning to the parameters of the model.Trends in the observed reactivity are explained by a change in the degree of association of one of the reactants to the micelles(Ru(NH_3)_5pz~(2+)in the present work).This association is governed by an equilibrium constant that depends on the electrostatic potential at the surface of the micelles.