Synthesis, structural, and spectral studies of diorganotin(IV) complexes with 2–hydroxy-5-methylbenzaldehyde-N(4)-cyclohexylthiosemicarbazone

Abstract

Three new diorganotin(IV) complexes, [Me2Sn(L)] (2), [Bu2Sn(L)] (3), and [Ph2Sn(L)] (4) [where H2L (1) = 2-hydroxy-5-methylbenzaldehyde-N(4)-cyclohexylthiosemicarbazone] have been synthesized by reacting the corresponding diorganotin(IV) dichloride with H2L (1) in absolute methanol in the presence of potassium hydroxide. All the compounds have been characterized by CHN analyses, UV–vis, FT-IR, 1H, 13C, and 119Sn NMR spectroscopy. The molecular structures of H2L (1) and 2 have been confirmed by single crystal X-ray diffraction analysis. H2L (1) is found to be in the thiol tautomeric form. The X-ray structure of 2 showed that H2L is a tridentate ligand and binds to the tin(IV) atom via the phenolic oxygen, azomethine nitrogen, and thiolate sulfur. Complex 2 has a triclinic structure and the coordination geometry of tin(IV) is distorted trigonal bipyramidal. The sulfur and oxygen are in axial positions while the azomethine nitrogen of 1 and two methyl groups occupy the equatorial positions. The C-Sn-C angles determined from 1J(119Sn, 13C) for 2, 3, and 4 are 124.35°, 123.11°, and 123.82°, respectively. The values of δ(119Sn) for 2, 3, and 4 are −153.4, −180.59, and −158.3 ppm, respectively, indicating five-coordinate tin(IV). From NMR data a distorted trigonal-bipyramidal configuration at each tin is proposed.