Synthesis, crystal structures and spectral characterization of diorganotin compounds with phenylglyoxylic acid isonicotinyl hydrazone

The synthesis and characterization of three organotin(IV) compounds with phenylglyoxylic acid isonicotinyl hydrazone (L) are reported. These compounds with the Schiff base ligand of the type – [R2SnLxYy]z (x = y = 1, z = 2: R1 = CH3, Y1 = EtOH for compound 1 or R2 = C6H5, Y2 = H2O for compound 2; and x = 2, y = 0, z = 1, R = n-C4H9 for compound 3) are characterized by IR, 1H, 13C NMR and elemental analysis. The crystal structures of the Schiff base ligand and the corresponding compounds have been determined by X-ray diffraction. In compounds 1 and 2, the tin atom is seven-coordinate in a distorted pentagonal bipyramid geometry chelating by the Schiff base ligand in an enolic tridentate fashion, forming a Sn2O2 ring, only with different coordinated solvent, water for 2 and ethanol for 1. However, in compound 3, there exists two different coordinate modes for the same ligand, one type of the usual enolic tridentate and the other type of unique carboxylate monodentate coordination without the participation of the amide group, this results in the central tin atom presenting six-coordinate in a distorted octahedron geometry. Fascinatingly, the supramolecular infrastructures were observed in the Schiff base ligand and three compounds, which exist either as two-dimensional sheets or as three-dimensional networks assembled from the organometallic subunits through intermolecular OH⋯X or CH⋯X (XO or N) hydrogen bonds.