Preparation and structural characterization of [Ph3Sn(IV)]+ complexes with pyridine-carboxylic acids or hydroxypyridine, -pyrimidine and -quinoline

A number of [Ph3Sn(IV)]+ complexes formed with ligands containing –OH (–Cdouble bond; length as m-dashO), or –COOH group(s) and aromatic {N} 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 119Sn Mössbauer nuclear quadrupole splittings, |Δexp| – according to the point charge model formalism – together with the FT-IR data support the formation of trigonal bipyramidal (Tbp) or octahedral (Oh) molecular structures. Furthermore, X-ray diffraction analysis has been performed on the triphenyltin(IV)-3-phenolato-2(1H)-pyridinone-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).