Weakly-bridged dimeric diorganotin(IV) compounds derived from pyruvic acid hydrazone Schiff base ligands: Synthesis, characterization and crystal structures

We report the synthesis of four diorganotin(IV) compounds of Schiff base pyruvic acid hydrazone derivatives formulated as [R2SnLY](2), where L-1 is 2-SC4H3CON2C(CH3)CO2 with Y = CH3CH2CH2CH2OH, R = n-Bu (1); L-2 is C6H5CON2C(CH3)CO2 With Y = CH3CH2OH, R = p-F-Bz (2); L-3 is 2-HOC6H4CON2C(CH3) CO2 with Y=H2O, R = p-CN-Bz (3); and L-4 is 4-NO2-C6H4CON2C(CH3)CO2 with Y=CH3CH2OH, R = Bz (4). The structures of all compounds have been established by a combination of single-crystal X-ray diffraction analysis, H-1 and Sn-119 NMR spectroscopy, IR spectroscopy, and elemental analysis. Studies reveal that four ligands present the same coordination mode with tin center, which all present tridentate ONO donor Schiff bases and coordinate to the tin center in an enolic form. In compounds 1-4, each tin atom is seven-coordinated and exhibits a distorted pentagonal bipyramid with a planar SnO4N unit and two apical alkyl carbon atoms, thus forming a weakly-bridged dimeric molecule. Additionally, the distance of Sn center dot center dot center dot O bridge in each compound is obviously affected by the choice of different alkyl groups and coordination solvent molecules, which fluctuates in the range of 2.571(5)-2.839(4) angstrom. Furthermore, the supramolecular structure analysis show that there are two types of supramolecular infrastructures, 1D chain or 2D network, which are formed by intermolecular O-H center dot center dot center dot N or C-H center dot center dot center dot X (X = O, N or F) hydrogen bonds. (C) 2010 Elsevier Masson SAS. All rights reserved.