Rapid reactions of solvate exchange in gadolinium (3) solutions

Temperature dependences of ESR and PMR spectra line widths of gadolinium (3) solutions in dehydrated organic solvents are studied. For some of the solvents on the basis of the dependence rate constants and activational parameters of solvate exchange reactions are determined. The exchange rate constant values obtained are in a good agreement with the solvent donor numbers. The absence of high-temperature broadening of ESR spectra line in certain solvents is related to the presence in solution of commensurable amounts of gadolinium (3) complexes with coordination numbers 8 and 9, between which rapid solvate exchange takes place in ESR time scale. Under the effect of steric factor in the series of solvents methanol-ethanol-isopropanol the character of exchange activation reactions changes from associative to dissociative one