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

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.