Syntheses and crystal structures of Pb(SeO3)2 and two modifications of Sn(SeO3)2

Single crystals of two modifications of Sn(SeO3)(2) have been synthesized from SnCl2, SeO2 and H2O at low-hydrothermal conditions (T = 490 K), tiny crystals of Pb(SeO3)(2) were precipitated at T = 363 K from solutions of SeO2 (aq.) and Pb(CH3COO)(4) in pure acetic acid. The structures were determined from CCD X-ray diffraction data and refined to R1 = 0.019, 0.029 and 0.045, respectively alpha-Sn(SeO3)(2): space group Pa (3) over bar, a = 8.1725(5) angstrom, V = 545.84(6) angstrom(3), Z = 4. beta-Sn(SeO3)(2) and Pb(SeO3)(2): space group P2(1)/c, a = 4.784(1)/4.811(2), b = 8.529(1)/8.768(4), c = 6.943(1)/7.079(3)angstrom, beta = 111.01(1)/110.10(2)degrees, V = 264.43(7)/280.4(2)angstrom(3), Z = 2. beta-Sn(SeO3)(2) and Pb(SeO3)(2) crystallize isotypic in a structure type known from Ti(SeO3)(2), while alpha-Sn(SeO3)(2) is structurally related to Me2+(NO3)(2) compounds. Both structure types are built from Me4+O6 (Me = Sn, Pb) octahedra, which are interlinked by trigonal pyramidal SeO3 groups via common corners to framework structures. (c) 2005 Elsevier B.V. All rights reserved.