Inner-sphere oxidation of diaqua(nitrilotriacetato)cobaltate(II) by periodate in acetate medium. Isokinetic relationship for the oxidation of (aminopolycarboxylato)cobalt(II) complexes by periodate

Abstract

The kinetics of oxidation of [Co^II(nta)(H₂O)₂]^–(nta = nitrilotriacetate) by periodate in acetate medium has been found to obey equation (i). Formation of initial cobalt(III) products, which were slowly converted to final cobalt(III) products, appears to fit an inner-sphere mechanism. A common d[Co^III]//_dt=(k₂′+k₃[CH₃CO₂^–])[Co^II(nta)(H₂O)₂^–][IO₄^–](i) mechanism for the oxidation of (aminopolycarboxylato)cobalt(II) complexes by periodate is proposed, and this is supported by an excellent isokinetic relationship between ΔH^‡ and ΔS^‡ values for these reactions.