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 (LMCl2)-M-1,2 (1-4: for L-1, M = Sb (1), Bi (3); for L-2, M = Sb (2), Bi (4)) containing ligands L-1,L-2 (where L-1 = C6H3-2,6-(CH=N-t-Bu)(2), L-2 = 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 (H-1 and C-13 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 (LBiR2)-Bi-1,2' (11-13: for L-1, R' = Me (11), Ph (12); for L-2, R' = Me (13)) as products of substitution of chlorine atoms. Compounds 5-13 were characterized by the help of H-1 and C-13 NMR spectroscopy. The molecular structures of 8, 9, and 13 were unambiguously established using single-crystal X-ray diffraction analysis.