EXAFS and Ligand Exchange Reaction of Hydrated 3d Transition Metal Complexes

Abstract

Relation between EXAFS parameters and ligand exchange reaction rate constant in solution is investigated. The EXAFS spectra of hydrated 3d metal complexes have been obtained over the temperature range of 20 K to 300 K. The temperature dependences of the mean square relative displacement σ2 and the third order coefficient C3 in cumulant expansion of EXAFS signal are examined for the first nearest metal-oxygen bond. The ligand exchange rate constant correlates not only with σ2 but also C3 both obtained from the EXAFS for solid hydrated complexes, and the higher the rate constant, the more rapidly σ2 and C3 increase with temperature.