Biological activity studies on organotin(IV)n+ complexes and parent Compounds

This review summarized the literature and own data on the parent organotin(IV) compounds and complexes formed with biologically active ligands

Preparation and structural characterization of Ph3Sn(IV)+ complexes with pyridinecarboxylic acids or hydroxypyridene, -pyrimidine and –quinoline.

A number of [Ph3Sn(IV)](+) complexes formed with ligands containing -OH (-C=O), or -COOH group(s) and aromatic IN) donor atom have been prepared. The binding sites of the ligands were identified by FT-IR spectroscopic measurements. In the complexes containing hydroxy and carboxylate functions, the carboxylato group is coordinated to the organotin(IV) centres in monodentate or bridging bidentate manner. It was also found that in the hydroxypyridine and -pyrimidine complexes the [Ph3Sn(IV)]+ moiety in most cases reacts with the phenolic form of the ligands. The rationalisation of the experimental Sn-119 Mossbauer nuclear quadrupole splittings, vertical bar Delta(exp)vertical bar - according to the point charge model formalism - together with the FT-IR data support the formation of trigonal bipyramidal (Tbp) or octahedral (O-h) molecular structures. Furthermore, X-ray diffraction analysis has been performed on the triphenyltin(IV)-3-phenolato-2(1H )-pyriditione-O,O' single crystals. The penta-coordinated tin center exhibits a Tbp geometry. In case of 2-picolinic acid, a trans-phenylation was observed during the complexation, resulting [Ph2Sn(IV)](2+) complex and Ph4Sn(IV). (c) 2005 Elsevier B.V. All rights reserved

Characterization of complexes formed between [Me2Sn(IV)]2+ and carboxymethylcelluloses.

Complexes formed between carboxymethylcellulose (CMC) and the [Me2Sn(IV)]2+ cation have been prepared in the solid state and characterized by FTIR and Mössbauer spectroscopy. The complexes contained CMC with varying molar weight and degree of carboxylation, and the complexes were isolated both from acidic and from neutral solutions at varying metal-to-ligand ratios. The characteristic vibration bands of the ligands were identified from their pH-dependent FTIR spectra. In the organotin(IV) complexes obtained at pH ∼2, the –COO− moieties were found to be coordinated in a monodentate manner, and the band characteristic of the protonated (unbound) –COO− group(s) was also identified. The broad –OH band can be interpreted as the sum of the contributions of the alcoholic –OH groups of the anhydroglucose units and the mixed organotin aqua complexes. In complexes obtained at pH ∼7, the broad –OH band significantly sharpens, which is probably due to the metal-ion induced deprotonation and subsequent coordination of the alcoholic –OH groups. At the same time, –COO− groups are also involved in the coordination of the metal ions, resulting in a complicated network that forms through inter- and intramolecular bridges. Quadrupole splitting (∣Δexp∣) values observed by Mössbauer spectroscopy revealed that the valence state of tin is four in all of the complexes. The ∣Δexp∣ values were compared with the calculated ones, obtained from the pqs theory. From these data, trigonal bipyramidal (Tbp) and octahedral (Oh) geometries have been suggested for the complexes obtained. It has also been concluded that the structure of the complexes prepared depends mainly on the pH of the solution, and it is relatively insensitive to the other parameters, like molar mass or degree of carboxylation of the ligand, or the metal-to-ligand ratio in the reaction mixtur