Pentadentate thiosemicarbazones as versatile chelating systems. A comparative structural study of their metallic complexes

Abstract

We have prepared some transition and post-transition metal complexes derived from the pentadentate thiosemicarbazone ligand bis(4-N-ethylthiosemicarbazone)-2,6-diacetylpyridine H₂L^Et, by both chemical and electrochemical procedures. The complexes have been synthesised and fully characterised, including the crystal structures for the ligand H₂L^Et and its manganese, cadmium and lead complexes. We have also performed multinuclear ¹⁰⁹Ag, ¹¹³Cd, ¹¹⁹Sn and ²⁰⁷Pb studies for silver, cadmium, tin and lead compounds, respectively. Moreover we present here a comparative study on the different structures found for pentadentate thiosemicarbazonate complexes, trying to check the influence of different factors, such as experimental procedure, size of metal, structure of the ligand, and metal oxidation state, on the final structure of the complex formed. Our aim is gaining a better insight into the coordination trends of pentadentate thiosemicarbazone ligands.