Self-assembly of organotin(IV) moieties with the Schiff-base ligands pyruvic acid isonicotinyl hydrazone and pyruvic acid salicylhydrazone: Synthesis, characterization, and crystal structures of monomeric or polymeric complexes

A series of organotin(IV) complexes of the type [R2SnLY](2) or [R2SnL(R3SnOH)](2) [L = 4-NC5H4CON2C(CH3)CO2 or 2HOC(6)H(4)CON(2)C(CH3)CO2, and Y = H2O or CH3OH] have been synthesized by the condensation reaction of R2SnO (R = Ph 1, nC(8)H(17) 2) or R3SnCl (R = o-ClBz 3, o-FBz 4, p-FBz 5, p-CNBz 6) with the Schiff-base ligand pyruvic acid isonicotinyl hydrazone in a 1:1 molar ratio or (R3Sn)(2)O (R = nBu 7, Bz 8, p-CNBz 9) or R3SnCl (R = o-ClBz 10, p-ClBz 11, p-CNBz 12) with the Schiff-base ligand pyruvic acid salicylhydrazone in a 1:1 molar ratio. All complexes were characterized by elemental analysis and IR, H-1, and Sn-119 NMR spectroscopy. The crystal structures of complexes 1, 2, 3, 7, and 10 have been determined by X-ray single crystal diffraction analyses, which show that the tin atoms of 1, 2, 3, and 10 are all seven-coordinate in distorted pentagonal bipyramid geometries, of which only complex I exhibits an asymmetric structure containing two different types of tin atoms. The crystal structure of 7 exhibits a dimeric structure containing distannoxane units with two types of tin atoms, in which one tin atom appears to be seven-coordinate with a distorted pentagonal bipyramid geometry and the other is four-coordinate with a distorted tetrahedral geometry. A comparison of the IR spectra of the ligands with those of the corresponding complexes reveals that the ligands coordinate to tin in the enol form due to the disappearance of the bands assigned to the carbonyl group. (c) Wiley-VCH Verlag GmbH and Co. KGaA, 69451 Weinheim, Germany, 2005.