EXAFS AND LIGAND-EXCHANGE REACTION OF HYDRATED 3D TRANSITION-METAL COMPLEXES

Relation between EXAFS parameters and ligand exchange reaction rate co nstant in solution is investigated. The EXAFS spectra of hydrated 3d m etal complexes have been obtained over the temperature range of 20 K t o 300 K. The temperature dependences of the mean square relative displ acement sigma2 and the third order coefficient C3 in cumulant expansio n of EXAFS signal are examined for the first nearest metal-oxygen bond . The ligand exchange rate constant correlates not only with sigma2 bu t also C3 both obtained from the EXAFS for solid hydrated complexes, a nd the higher the rate constant, the more rapidly sigma2 and C3 increa se with temperature.