Structural Diversity of Organoantimony(III) and Organobismuth(III) Dihalides Containing O,C,O-Chelating Ligands

Eight organoantimony and organobismuth dihalides, containing two types of O,C,O-chelating (so-called pincer) ligands, 2,6-(ROCH<sub>2</sub>)C<sub>6</sub>H<sub>3</sub><sup>-</sup> (R = Me, L<sup>1</sup>; R = <i><sup>t</sup></i><sup></sup>Bu, L<sup>2</sup>; L<sup>1</sup>SbCl<sub>2</sub> (<b>1</b>), L<sup>2</sup>SbCl<sub>2</sub> (<b>2</b>), L<sup>1</sup>SbI<sub>2</sub> (<b>3</b>), L<sup>2</sup>SbI<sub>2</sub> (<b>4</b>), L<sup>1</sup>BiCl<sub>2</sub> (<b>5</b>), L<sup>2</sup>BiCl<sub>2</sub> (<b>6</b>), L<sup>1</sup>BiI<sub>2</sub> (<b>7</b>), L<sup>2</sup>BiI<sub>2</sub> (<b>8</b>)) were prepared and characterized with the help of elemental analysis, electrospray ionization mass spectrometry, <sup>1</sup>H and <sup>13</sup>C NMR spectroscopy, and X-ray diffraction techniques. Except for <b>5</b>, which exists as a centrosymmetric dimer, all studied compounds are monomeric in the solid state and the coordination polyhedra of the central atoms are distorted square-pyramidal. Both oxygen donor atoms are coordinated to the central metal through moderately strong or strong intramolecular interactions (range of Sb−O distances 2.279(2)−2.6912(14) Å and Bi−O distances 2.379(3)−2.460(4) Å), both in <i>cis</i> fashion for <b>1</b> and <b>2</b> (angles O−Sb−O 116.65(5)° and 116.73(4)°) and <i>trans</i> fashion for <b>3</b>, <b>4</b>, and <b>6</b>−<b>8 </b>(range of angles O−M−O; M = Sb or Bi, 142.26(12)−148.28(8)°). In noncoordinating solvents (CDCl<sub>3</sub>, toluene-<i>d</i><sub>8</sub>) <b>1</b>−<b>8</b> display structures similar to those found in the solid state based on variable-temperature <sup>1</sup>H NMR measurements.