Kinetics of 1 : 1 chelate formation between 2-acetylcyclopentanone and oxovanadium(IV)

The kinetic parameters of the 1:1 chelate complex of 2-acetylcyclopentanone with the oxovanadium(IV) ion in aqueous solution at 25 degreesC and 0.5 mo l dm(-3) ionic strength are reported. A spectrophotometric study indicates that the species present in solutions of oxovanadium(IV) ion and of 2-acety lcyclopentanone below pH 2 can be formulated as 1:1 complexes of the type V O(C7H9O2)(+) The kinetic data are consistent with a scheme in which both th e enol form of the ligand and the enolate ion react with the oxovanadium(IV ) ion. From a study of the kinetic results over a range of temperatures, su bsequent activation parameters for the chelation processes, DeltaH double d agger and DeltaS double dagger, were determined, Some discussions are provi ded on the basis of the Eigen-Wilkins theory considering the effect of solv ent exchange on the chelation process. Copyright (C) 2000 John Wiley & Sons , Ltd.