Synthesis and structural characterization of diorganotin(IV) esters with pyruvic acid isonicotinyl hydrazone and pyruvic acid salicylhydrazone Schiff bases

Eight diorganotin esters of Schiff base ligands formulated as [R2SnLY]2, where L1 is 4-NC5H4CON2C(CH3) CO2 with Y = H2O, R = Ph (1), PhCH2 (2), m-ClC6H4CH2 (3), and L2 is 2-HOC6H4CON2C(CH3) CO2 with Y = CH3OH, R = PhCH2 (4), o-ClC6H4CH2 (5), m-ClC6H4CH2 (6), o-FC6H4CH2 (7), p-FC6H4CH2 (8) have been prepared and characterized by elemental analysis, IR, 1H and 119Sn NMR spectra. The crystal structures of compounds 1, 2 and 4 have been determined by X-ray single crystal diffraction. Their structures show that the tin atoms of three compounds are all rendered seven-coordinated in distorted pentagonal bipyramid geometries with a planar SnO4N unit and two apical aryl carbon atoms. A comparison of the IR spectra of the ligands with those of the corresponding compounds, reveals that the disappearance of the bands assigned to carbonyl unambiguously conforms that the ligands coordinate with tin in the enol form.