Crystal chemistry of natural and synthetic lead oxohalides: II. Crystal structure of Pb7O4(OH)4Br2
- 43 Downloads
Crystals of lead oxobromide Pb7O4(OH)4Br2 have been synthesized by hydrothermal method. The structure of the new compound has been studied with X-ray single-crystal diffraction analysis. The compound is monoclinic, space group C1121; unit-cell dimensions are a = 5.852(4), b = 13.452(7), c = 19.673(9) Å, γ = 90.04°, V = 1548.7(15) Å3. The structure has been solved by direct methods and refined to R 1 = 0.1138 for 1847 observed Pb7O4(OH)4Br2 unique reflections. The structure contains seven symmetrically independent bivalent Pb atoms. The coordination polyhedrons of Pb are strongly distorted due to stereochemical activity of unshared electron pair 6s 2. Oxygen atoms are tetrahedrally coordinated by four Pb2+ cations with the formation of oxocentered tetrahedrons OPb4. The compound is based on [O2Pb3]2+ double chains formed by OPb4 tetrahedrons. (OH)Pb2 dimers combine the [O2Pb3]2+ chains into 3D framework. Channels in the framework are parallel to  and are occupied by Br anions.
KeywordsCrystal Chemistry Double Chain CuPb Lead Chloride Litharge
Unable to display preview. Download preview PDF.
- 1.N. E. Brese and M. Keeffe, “Bond-Valence Parameters for Solids,” Acta Crystallogr. B47, 192–197 (1991).Google Scholar
- 3.J. J. Finney, E. J. Graeber, and A. Rosenzweig, “The Structure of Chloroxiphite, Pb3CuO2(OH)2Cl2,” Mineral. Mag. 41, 457–361 (1997).Google Scholar
- 4.M. Kiyama, K. Murakami, T. Takada, et al., “Formation and Solubility of Basic Lead Chlorides at Different PH Values” (Chem. Lett., 1976), pp. 23–28Google Scholar
- 9.S. V. Krivovichev and P. C. Burns, “Crystal Chemistry of Lead Oxide Chlorides. I. Crystal Structure of Pb2O2(OH)4Cl2,” Eur. J. Mineral. 14, 135–139 (2002).Google Scholar
- 10.S. V. Krivovichev and S. K. Filatov, Crystal Chemistry of Minerals and Inorganic Compounds with Complexes of Anion-Centered Tetrahedrons (St.-Petersburg State Univ., St. Petersburg, 2001) [in Russian].Google Scholar
- 14.O. I. Siidra, S. V. Krivovichev, and V. Depmeier, “Crystal Chemistry of Natural and Synthetic Pb Oxogalogenides. I. Crystalline Structure of Rb13O10Cl6,” Zap. Russian Mineral. O-va 136(4), 79–89 (2007) [Geol. Ore Deposits 136 (Spec. Issue 8, Zapiski Russian Mineral. Soc.), 827–834 (2007)].Google Scholar