Syntheses and Crystal Structures of PbSbO 2 Br, PbSbO 2 I, and PbBiO 2 Br

Transparent single crystals of PbSbO 2 Br (green), PbSbO 2 I, and PbBiO 2 Br (yellow) were obtained by solid state reactions of stoichiometric amounts of PbO, Pn 2 O 3 ( Pn = Sb, Bi) and PnX 3 ( X = Br, I). The crystal structures were determined from single‐crystal X‐ray data. The title compounds crystallize tetragonally in the space group I 4/ mmm (No. 139): Lattice constants and refinement values are: PbSbO 2 Br: a = 3.9463(3), c = 12.849(1) Å, V = 200.10(3) Å 3 , and Z = 2, R 1 = 0.0236, and wR 2 = 0.0513. PbSbO 2 I: a = 4.0074(3), c = 13.627(2) Å, V = 218.84(3) Å 3 , and Z = 2, R 1 = 0.0244, and wR 2 = 0.0538. PbBiO 2 Br: a = 3.9818(2), c = 12.766(2) Å, V = 202.39(4) Å 3 , and Z = 2, R 1 = 0.0276, and wR 2 = 0.0715. The compounds are isotypic and crystallize in the anti ‐ThCr 2 Si 2 structure type with lead and Pn statistically disordered on one common position. In case of Pn = Sb a slight separation of the positions of the cations becomes obvious. Optical bandgaps were determined by UV/Vis spectroscopy. They are 2.67 eV (PbSbO 2 Br), 2.48 eV (PbSbO 2 I), and 2.47 eV (PbBiO 2 Br).