Analytical Sciences

X-Ray Crystallographic Approach to the Design of Phenolic Schiff Base Reagents for the Mutual Separation of Lanthanoids

Koji KUBONO,*  Naoki HIRAYAMA,** Hisao KOKUSEN,*** and Kunihiko YOKOI*

*Division of Natural Science, Osaka Kyoiku University, Kashiwara, Osaka 582-8582, Japan
**Department of Chemistry, Faculty of Science, Kanazawa University, Kanazawa 920-1192, Japan
***Department of Chemistry, Faculty of Education, Tokyo Gakugei University, Koganei, Tokyo 184-8501, Japan

A novel mutual selectivity of lanthanoids in the N,N-bis(5-nitrosalicylidene)ethylenediamine (H₂Nsalen)-KCl and N,N-bis(5-nitrosalicylidene)-o-phenylenediamine (H₂Nsaloph)-KCl extraction systems was evaluated by the X-ray analysis of similar model complexes for extracted species. Cerium(IV) complexes with N,N-bis(5-chlorosalicylidene)-ethylenediamine (H₂Clsalen), N,N-bis(salicylidene)-o-phenylenediamine (H₂saloph) and N,N-bis(3,5-dibromosalicylidene)-o-phenylenediamine (H₂Br₂saloph) were selected as the models. The result of the X-ray analysis suggested that [Ln(III)(Nsalen)₂]^- and [Ln(III)(Nsaloph)₂]^- are meridional type (two ligands are oriented perpendicular to each other) and sandwich type (two ligands are oriented parallel to each other), respectively. It was suggested that the selectivity of the meridional structure is superior to that of the sandwich structure in these extraction systems.

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