Solvent extraction of groups 4 and 14 metal chelate complexes: Model experiments for chemical studies on coordination number of element 104

Abstract

To verify the idea that the coordination number of element 104 could be influenced by relativistic effects the studies on complexation of possible homologs of element 104 in group 4 (Zr⁴⁺, Hf⁴⁺, Ti⁴⁺) and 14 (Sn⁴⁺, Pb⁴⁺) by thenoyltrifluoroacetone (TTA) and tropolone (T) were performed. Contrary to monodentate ligands, TTA forms octacoordinate complexes not only with Zr⁴⁺ and Hf⁴⁺ but also with Ti⁴⁺, which are extracted to organic phase. Tropolone forms octacoordinate neutral complexes also with group 14 metal cations Sn⁴⁺ and Pb⁴⁺. Since octacoordinate complexes of Ti⁴⁺, Sn⁴⁺ and Pb⁴⁺ with TTA and T are much weaker than the respective complexes of Zr⁴⁺ and Hf⁴⁺, extraction of the former complexes to organic phase requires higher values of pH. The behavior of 104⁴⁺ in experiments with TTA or T extractants should answer the question concerning the similarity of 104⁴⁺, in respect to CN to its lighter congeners Zr⁴⁺ and Hf⁴⁺ or Ti⁴⁺ and group 14 elements.