Synthesis and structure of enaminoketones of pyrazole containing 2-thione(selenone)benzimidazolyl fragments and their zinc and cadmium complexes

Abstract

New ligand systems based on 4-formyl-5-hydroxypyrazole and 1-aminobenzimidazole derivatives are synthesized. The obtained enamines and their Zn²⁺ and Cd²⁺ metal complexes of composition ML₂ were investigated using the IR, heteronuclear (¹H, ¹³C, ¹⁵N, ⁷⁷Se, ¹¹³Cd) and two-dimensional NMR spectroscopy (COSY, HSQC, HMBC). The data of physicochemical investigations and quantum-chemical calculations showed that the ligands exist in the ketoamine tautomeric form. Quantum-chemical simulation of Zn(II) and Cd(II) complexes showed that the zinc complexes adopt the pseudo-tetrahedral and the cadmium complexes pseudo-octahedral configuration.