Search

The coordinative chemistry of the tridentate thiosemicarbazone ligand 2-pyridinecarboxaldehyde 4-N-ethylthiosemicarbazone (HLEt) has been explored by using an electrochemical methodology. All the complexes have been characterized using analytical and spectroscopic techniques. In the case of copper we have isolated two different complexes, with Cu(LEt)2·4H2O (6) and [Cu2(LEt)2(SO4)] (7) formulae. The sulfate group coordinated to the copper atoms in 7was probably released to the media as a consequence of a desulfurization process. Single X-ray crystallography has been carried out for the ligand HLEtand the complexes 7, [Ag6(LEt)6]·CH3CN (9) and [Pb(LEt)2] (12). The copper(ii) complex 7is a dimer compound in which two antiparallel monodeprotonated ligands are coordinated to two copper centres by establishment of μ2-thiolate bridges and the additional coordination of a sulfate group bridging the two metal atoms. The silver complex 9is an unusual hexanuclear cluster compound with a wheel-type conformation, while the lead complex 12is a monomer which exhibits the lone pair effect. A structural comparative study of the electrochemically obtained complexes derived from HLXligands (X= Me, Et and Ph) have been performed. Finally, the solution behaviour of the complexes was checked by NMR, UV and fluorescence studies. [ABSTRACT FROM AUTHOR]

We have prepared some transition and post-transition metal complexes derived from the pentadentate thiosemicarbazone ligand bis(4-N-ethylthiosemicarbazone)-2,6-diacetylpyridine H2LEt, by both chemical and electrochemical procedures. The complexes have been synthesised and fully characterised, including the crystal structures for the ligand H2LEtand 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. [ABSTRACT FROM AUTHOR]