Synthesis and structure of N,C-chelated organoantimony(v) and organobismuth(v) compounds

Abstract

The reaction of N,C-intramolecularly coordinated organoantimony(III) and organobismuth(III) compounds LMCl₂ (M = Sb (1) or Bi (2) and L = [o-(CHN-2,6-iPr₂C₆H₃)C₆H₄]) with phenyllithium in a 1 : 1 or 1 : 2 molar ratio gave compounds LM(Ph)Cl (M = Sb (3) or Bi (4)) and LMPh₂ (M = Sb (5) or Bi (6)) in moderate to good yields. Compound 3 could also be prepared by the treatment of the lithium compound LLi with in situ prepared PhSbCl₂. Oxidation of the antimony(III) compounds 1, 3 and 5 with one equivalent of SO₂Cl₂ proceeded smoothly with formation of organoantimony(V) compounds LSbCl₄ (7), LSb(Ph)Cl₃ (8) and LSbPh₂Cl₂ (9) in nearly quantitative yields. Compounds 7–9 are yellowish solids that are stable for a long time even in the presence of air. In contrast, only organobismuth(III) compounds 4 and 6 could be successfully oxidized using SO₂Cl₂ to give compounds LBi(Ph)Cl₃ (10) and LBiPh₂Cl₂ (11). Compound 11 is stable, but compound 10 readily decomposed in solution and could not be isolated and stored for a longer period. All attempts to prepare compound LBiCl₄ by the oxidation of 2 with SO₂Cl₂ failed and resulted only in a mixture of products. All studied compounds were characterized by electrospray ionization (ESI) mass spectrometry, and ¹H and ¹³C NMR spectroscopy. The molecular structures of 3–7, 9 and 11 were unambiguously established using single-crystal X-ray diffraction analysis.