New chiral organoantimony(III) compounds containing intramolecular N → Sb interactions – solution behaviour and solid state structures

Hypervalent organoantimony(III) compounds of the type [2-(Me₂NCH₂)C₆H₄]PhSbCl (1), [2-(Me₂NCH₂)C₆H₄]MesSbBr (7) and [2-(Me₂NCH₂)C₆H₄]_nAr_3−nSb [n = 1, Ar = Ph (4), Mes (9); n = 2, Ar = Ph (5), Mes (10)] were prepared via salt elimination reactions between [2-(Me₂NCH₂)C₆H₄]Li and MesMgBr and Ph_nSbCl_3−n, [2-(Me₂NCH₂)C₆H₄]SbBr₂ or [2-(Me₂NCH₂)C₆H₄]_nSbCl_3−n (n = 1, 2), in appropriate molar ratios. Halogen exchange reactions with aqueous KBr or KI gave [2-(Me₂NCH₂)C₆H₄]ArSbX [Ar = Ph, X = Br (2), I (3); Ar = Mes, X = I (8)]. Metathesis reaction between 1 and MesMgBr affords [2-(Me₂NCH₂)C₆H₄]PhMesSb (6). Compounds 1–10 were investigated by means of NMR (¹H, ¹³C) in solution and by mass spectrometry. The investigation of the molecular structures of 2–8 by single-crystal X-ray diffraction revealed that the nitrogen atoms of the pendant CH₂NMe₂ arms are strongly coordinated to the antimony atoms. All compounds exhibit chirality and crystallize as racemic mixtures.