Activation energies of intermolecular dynamics in ethylenediaminetetraacetate complexes with lanthanides: An effect of the “gadolinium break”

1H NMR measurements are reported for the aqueous solutions of EDTA4− complexes with light lanthanides. Comparison ΔG‡298 values (of the intermolecular EDTA4− ions exchange at [Ln(H2O)n(EDTA4−)]−) for the light and the heavy lanthanides showed a “gadolinium break” of the dependence of the ΔG‡298 on the atomic number of lanthanide. Paramagnetic coordination compounds [Ln(H2O)n(EDTA4−)]− are lanthanide paramagnetic probes for in situ NMR temperature control in solution in case of the light lanthanides as well as for previously studied heavy ones. The work shows that the use of a new approach (analysis of the energy barriers of processes depending on the atomic number of lanthanide) provides a radically new information even for classical systems.88