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-(ROCH2)C6H3- (R = Me, L1; R = tBu, L2; L1SbCl2 (1), L2SbCl2 (2), L1SbI2 (3), L2SbI2 (4), L1BiCl2 (5), L2BiCl2 (6), L1BiI2 (7), L2BiI2 (8)) were prepared and characterized with the help of elemental analysis, electrospray ionization mass spectrometry, 1H and 13C NMR spectroscopy, and X-ray diffraction techniques. Except for 5, 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 cis fashion for 1 and 2 (angles O−Sb−O 116.65(5)° and 116.73(4)°) and trans fashion for 3, 4, and 68 (range of angles O−M−O; M = Sb or Bi, 142.26(12)−148.28(8)°). In noncoordinating solvents (CDCl3, toluene-d8) 18 display structures similar to those found in the solid state based on variable-temperature 1H NMR measurements.