Synthesis of complexes of dimethyltin(IV) with mono- and di-deprotonated pyridoxine (PN) in media with various anions. Crystal structures of [SnMe2(PN – H)]NO3·2H2O, [SnMe2(H2O)(PN – H)]Cl·H2O and [SnMe2(H2O)(PN – 2H)]·0.5H2O

Abstract

The reaction of the dimethyltin(IV) cation with pyridoxine [3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridine, PN] has been investigated in ethanol–water (80∶20 v/v) containing NO₃^– and Cl^–, NO₃^– and MeCO₂^– or Cl^– and MeCO₂^– ions in various mole ratios. The compounds [SnMe₂(PN – H)]NO₃·2H₂O 1, [SnMe₂(H₂O)(PN – H)]Cl·H₂O 2 and [SnMe₂(H₂O)(PN – 2H)]·0.5H₂O 3 were isolated and characterized by IR, Raman, cross polarization magic angle spinning ¹³C NMR and electron impact and FAB mass spectrometry. The structures of the compounds were determined by X-ray diffraction. In 1 [SnMe₂(PN – H)]₂²⁺ units in which each monodeprotonated pyridoxine co-ordinates to one tin atom via the phenolic O and a deprotonated CH₂OH group O and to the other via the latter group alone are connected in a polymeric structure via the other CH₂OH group of each PN – H. In each dimeric unit the tin atom is co-ordinated to two methyl groups, the phenolic O atom, the O atoms of two deprotonated CH₂OH groups, and the O atom of a non-deprotonated CH₂OH group. Hydrogen-bonded water and NO₃^– ions are also present in the crystal lattice. In 2 the lattice contains dimeric [SnMe₂(H₂O)(PN – H)]₂²⁺ units (in which the tin–pyridoxine co-ordination is the same as in 1 except that the bonds connecting different units in 1 now bind aqua ligands) and hydrogen-bonded water and chloride ions. In 3 the crystal contains dimeric [SnMe₂(H₂O)(PN – 2H)]₂ units (in which the dideprotonated ligand co-ordinates as in 2) and water. The behaviour of these compounds in D₂O and (CD₃)₂SO was studied by NMR spectroscopy.