Synthesis and structural characterization of organotin(IV) compounds derived from the self-assembly of hydrazone Schiff base series and various alkyltin salts

Reactions of pyruvic acid hydrazone series pyruvic acid thiophenecarbonyl hydrazone (L1), pyruvic acid 4-hydroxybenzoylhydrazone (L2), pyruvic acid salicyloylhydrazone (L3), pyruvic acid benzoylhydrazone (L4)], or salicylaldehyde hydrazone Schiff base ligand salicylaldehyde isonicotinoylhydrazone (L5)] with different alkyltin salts result in six new organotin(IV) compounds, {(n-Bu)₂Sn2-SC₄H₃CON₂C(CH₃)CO₂](HOC₃H₇-i)}₂ (1), {(n-Bu)₂SnCl(O)(n-Bu)₂ Sn(O)C₆H₄CON₂C(CH₃)CO₂]Sn(n-Bu)₂(HOCH₃)}₂]_∞ (2), {(o-ClBz)₂Sn4-HOC₆H₄CON₂C(CH₃) CO₂] (HOC₂H₅)}₂ (3), {(n-C₈H₁₇)₂Sn2-HOC₆H₄CON₂C(CH₃)CO₂](H₂O)}₂ (4), {(n-Bu)₂SnC₆H₅ CON₂C(CH₃)CO₂]HOSn(n-Bu)₃]}₂ (5), and {(n-C₄H₉)SnCl₂]⁻4-NHC₅H₄CON₂CH (C₆H₄O-2)]⁺ (6), which have been characterized by single crystal X-ray diffraction, elemental analysis, IR, ¹H and ¹¹⁹Sn NMR. In compounds 1, 3, 4, weak-bridged dimers are found, in which the two tin atoms are linked by a pair of monodentate bridges. Each pyruvic acid hydrazone ligand serves as an enolic tridentatic ligand. Compound 2 contains dimeric units of {Sn₆(L2)₂(n-Bu)₆(HOCH₃)₂} that are further connected by two pairs of monodentate bridges into an 1D weak-bridged polymeric chain, in which there also exists a fascinating dichlorodistannoxane ladder structure. Studies show that the bulk and steric hindrance of the alkyl groups and the coordinated solvent molecule bonding to Sn center have little effect on the geometry of the weak-bridge for compounds 1-4. A similar weak-bridged dimeric structure is also found in compound 5; in this case, however, there is no coordinated solvent molecule and the corresponding coordination site is replaced by the trialkyltin hydroxide. Compound 6 exhibits a rare 1D supermolecular chain constructed from the zwitterionic {Sn(L5)(n-Bu)Cl₂} units connected by the intermolecular N-H?Cl hydrogen bonds. The thermal stability of compound 1 was also studied.