Comparison of covalency in the lanthanide chloride and nitrate complexes based on the adsorption data on zeolite Y

The changes of the distribution constants Kd of lanthanide chlorides in the system: zeolite Y (solid phase)–sodium chloride (aqueous phase) were investigated. The evident tetrad effect in the change of log Kd values within the lanthanide series was observed and the attempt of its explanation through the comparison of covalence in LnO bonds existing in: the AlO(1/3Ln)Si, AlO(1/3Ln) species, i.e. those formed by siloxane and silanols in the zeolite phase and in the aquoions Ln(H2O)8–93+ present in the aqueous phase was presented. The Ln–zeolite samples were characterized by N2 adsorption and magnetic measurements. The magnetic moments were determined over the range of 77–303 K. They obey the Curie–Weiss law. The values of μeff calculated for Ln–zeolite Y are much higher than those obtained for Ln3+ by Hund and Van Vleck.

► The tetrad effect in the change of log Kd values was observed.
► The covalency in the lanthanide nitrato complexes is stronger than that in the chloride ones.
► The values of μeff (magnetic moments) for Ln–zeolite Y are much higher than those for Ln3+ by Hund and Van Vleck.