Preparation and characterization of diorgano- and dihalogeno-bis(monothio-β-diketonato)tin(IV) complexes. Crystal and molecular structures of SnY2(btbm)2 and SnY2(tacac)2(Y = Me or Cl)

Abstract

Diorgano- and dihalogeno-bis(monothio-β-diketonato)tin(IV) complexes have been prepared and their structures partially deduced by i.r. and n.m.r. data. In order to ascertain structural conclusions, X-ray crystal structure analyses were performed on the complexes SnMe₂(btbm)₂[Hbtbm = benzoyl(thiobenzoyl)methane] and SnMe₂(tacac)₂(Htacac = monothioacetylacetone), as well as their dichlorotin(IV) analogues, SnCl₂(btbm)₂ and SnCl₂(tacac)₂. The tin atoms in SnMe₂(btbm)₂ and SnMe₂(tacac)₂ show a strongly distorted octahedral environment with pairs of the same donor atoms (O, S) in the cis position. The two methyl groups deviate strongly from the trans position, C–Sn–C bond angles being 134.2 and 139.4° respectively. Comparatively long Sn–O bond distances reveal the anisobidentate nature of the ligand. In contrast, the dichloro complexes SnCl₂(btbm)₂ and SnCl₂(tacac)₂ exhibit octahedral geometries, the Cl–Sn–Cl bond angles being only 95.3 and 98.5° respectively, with the chlorine atoms in cis positions and the sulphur atoms in trans positions. The oxygen atoms show normal Sn–O bond lengths.