Organoantimony(iii) compounds containing (imino)aryl ligands of the type 2-(RNCH)C6H4 (R = 2′,4′,6′-Me3C6H2, 2′,6′-iPr2C6H3): bromides and chalcogenides

Abstract

The reaction of 2-(RNCH)C₆H₄MgBr [R = 2′,4′,6′-Me₃C₆H₂ (R¹), 2′,6′-ⁱPr₂C₆H₃ (R²)] [prepared from 2-(R¹NCH)C₆H₄Br (1) or 2-(R²NCH)C₆H₄Br (2) and Mg] with SbCl₃ in a 2 : 1 and 1 : 1 molar ratio followed by treatment with an aqueous KBr solution gave [2-(R¹NCH)C₆H₄]₂SbBr (3) and [2-(R²NCH)C₆H₄]₂SbBr (4) as well as [2-(R¹NCH)C₆H₄]SbBr₂ (6) and [2-(R²NCH)C₆H₄]SbBr₂ (7). Treatment of 4 with Na₂S·9H₂O provided the dinuclear [{2-(R²NCH)C₆H₄}₂Sb]₂S (5). Heterocyclic species, i.e. the oxide cyclo-[{2-(R²NCH)C₆H₄}SbO]₃ (8) and the sulfides cyclo-[{2-(R¹NCH)C₆H₄}SbS]₂ (9) and cyclo-[{2-(R²NCH)C₆H₄}SbS]₂ (10), were obtained by reacting dibromides 6 and 7 with KOH and Na₂S·9H₂O, respectively, in a water–toluene solvent mixture. The sulfide 10 reacted with [W(CO)₅(thf)] to yield the heterometallic complex cyclo-[{2-(R²NCH)C₆H₄}SbS]₂[W(CO)₅] (11). The compounds were characterised by multinuclear NMR spectroscopy in solution, mass spectrometry and IR spectroscopy in the solid state. The molecular structures of 4, 5, 6·CHCl₃, 7, 9·CH₂Cl₂, 10 and 11·0.25CH₃OH were established by single-crystal X-ray diffraction. Theoretical calculations using DFT methods were carried out on bromide 7 and the geometrical isomers of its dimer association as well as the geometrical isomers of sulfide 10 and its monomer.