Kinetics of the oxidation of iodide by copper(III)-imine-oxime complexes

Summary The copper(III)-imine-oxime complexes Cu^III(Enio)]⁺ and Cu^III(Pre)]⁺ {EnioH₂ =N,N-ethylene bis(isonitrosoacetylacetoneimine) and PreH₂ = N,N-propylene bis (isonitrosoacetylacetoneimine)} react very rapidly with iodide. The rate law under fixed conditions for the reaction is given by the equation: –dCu^III]/dt = (2k₂I^–] + 2k₃I^–]²)Cu^III] The Cu^III(Enio)]⁺ reaction was pH-independent whereas the Cu (Pre)]⁺ reaction rate increased with increasing pH. Both the k₂ and the k₃ pathways are believed to involve one-electron transfer. An inner-sphere mechanism may operate in the pathway, first-order in I^–].