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 L^1,2MCl₂ (<b>1</b>–<b>4</b>: for L¹, M = Sb (<b>1</b>), Bi (<b>3</b>); for L², M = Sb (<b>2</b>), Bi (<b>4</b>)) containing ligands L^1,2 (where L¹ = C₆H₃-2,6-(CHN-<i>t</i>-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 <b>1</b>–<b>4</b> were established both in solution (¹H and ¹³C NMR spectroscopy) and, in the case of <b>1</b>–<b>3</b>, in the solid state using single-crystal X-ray diffraction analysis. Treatment of antimony derivatives <b>1</b> and <b>2</b> with 2 molar equiv of R′Li (R = Me, <i>n</i>-Bu, Ph) yielded the set of substituted 1,3-(R′)₂-2-R-7-(CHNR)-1<i>H</i>-2,1-benzazastiboles <b>5</b>–<b>10</b> (where R = <i>t</i>-Bu, 2,6-Me₂C₆H₃ and R′ = Me, <i>n</i>-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 <b>2</b> and <b>4</b> and R′Li (2 equiv, R′ = Me, Ph) gave L^1,2BiR′₂ (<b>11</b>–<b>13</b>: for L¹, R′ = Me (<b>11</b>), Ph (<b>12</b>); for L², R′ = Me (<b>13</b>)) as products of substitution of chlorine atoms. Compounds <b>5</b>–<b>13</b> were characterized by the help of ¹H and ¹³C NMR spectroscopy. The molecular structures of <b>8</b>, <b>9</b>, and <b>13</b> were unambiguously established using single-crystal X-ray diffraction analysis