Synthesis and structures of hypervalent organoantimony and organobismuth chlorides containing asymmetric C,E,C-chelating (E = O, S) ligands

Abstract

Two asymmetric tridentate C,E,C-chelating ligand precursors, 1-Br-2-[(2′-BrC₆H₄CH₂E)CH₂]C₁₀H₆ (E = O (1), E = S (2), were prepared in good yield. Lithiation of the two precursors was achieved by a reaction with n-BuLi, and was followed by treatment with SbCl₃ or BiCl₃ in a 1 : 1 molar ratio to give four air-stable hypervalent organoantimony and organobismuth chlorides with an asymmetric C,E,C-chelating ligand (E = O, S), i.e. (C₆H₄CH₂OCH₂C₁₀H₆)SbCl (3), (C₆H₄CH₂SCH₂C₁₀H₆)SbCl (4), (C₆H₄CH₂OCH₂C₁₀H₆)BiCl (5) and (C₆H₄CH₂SCH₂C₁₀H₆)BiCl (6). These compounds were characterized by NMR spectroscopy, elemental analysis and melting point determination. X-ray structure analysis of compounds 3–6 revealed that the donor atoms (O, S) are strongly coordinated to the metal atoms (Sb, Bi). Compounds 3–6 exhibit chirality and crystallize as racemic mixtures.