Reactivity of N,C,N-Chelated Antimony(III) and Bismuth(III) Chlorides with Lithium Reagents: Addition vs Substitution

Abstract

N,C,N-chelated antimony(III) and bismuth(III) chlorides L1,2MCl2 (1–4: for L1, M = Sb (1), Bi (3); for L2, M = Sb (2), Bi (4)) containing ligands L1,2 (where L1 = C6H3-2,6-(CH═N-t-Bu)2, L2 = C6H3-2,6-(CH═N-2′,6′-Me2C6H3)2) were prepared by reactions of lithium precursors with SbCl3 or BiCl3. The identities of 1–4 were established both in solution (1H and 13C NMR spectroscopy) and, in the case of 1–3, in the solid state using single-crystal X-ray diffraction analysis. Treatment of antimony derivatives 1 and 2 with 2 molar equiv of R′Li (R = Me, n-Bu, Ph) yielded the set of substituted 1,3-(R′)2-2-R-7-(CH═NR)-1H-2,1-benzazastiboles 5–10 (where R = t-Bu, 2,6-Me2C6H3 and R′ = Me, n-Bu, Ph) as a result of a nucleophilic attack of one of the lithium compounds across the imino C═N functionality. In contrast, analogous reactions between bismuth congeners 2 and 4 and R′Li (2 equiv, R′ = Me, Ph) gave L1,2BiR′2 (11–13: for L1, R′ = Me (11), Ph (12); for L2, R′ = Me (13)) as products of substitution of chlorine atoms. Compounds 5–13 were characterized by the help of 1H and 13C NMR spectroscopy. The molecular structures of 8, 9, and 13 were unambiguously established using single-crystal X-ray diffraction analysis.