Crystal structure of sodium gallium [monohydrogenmonophosphatedihydrogenmonoborate- monophosphate], NaGa[BP2O7(OH)3

Abstract

BGaH3NaO10P2, monoclinic, C12/c1 (No. 15), a = 10.408(3) A, b = 8.094(2) A, c = 9.099(2) A, = 116.64(2)°, V = 685.2 A, Z = 4, Rgt(F) = 0.025, wRref(F ) = 0.068, T = 293 K. Source of material NaGa[BP2O7(OH)3] was synthesized under mild hydrothermal conditions. The reaction was carried out with mixtures of Ga metal (0.139 g) dissolved in 1ml of HCl (18%) with Na2HPO4·12H2O (1.075 g) and Na2B4O7·10H2O (0.4767 g) (molar ratio of Ga:P:B = 2:3:6) in aqueous solution. The mixture was sealed in glass tubes (after adding 1 ml H2O to achieve a degree of filling of 30%) with subsequent heating at 408 K for 60 days. The starting materials are all of analytical grade. Discussion With the increasing interest in microporous materials, synthesis of compounds like borophosphates with open framework structure have drawn much attention during the past few years and show a rich crystal chemistry [1]. Systems including a p-block metal have not been widely explored up to now besides one Al compound [2] reported only recently. The structure of the title compound is isotypic to the Fe [3] and Al analogues [2] and is characterized by isolated GaO4(OH)2 octahedra sharing common O-corners with phosphate and common O(OH)-corners with hydrogenborate groups from the ol igomeric uni ts [B2P2O7(OH)3]. The condensation of the borophosphate oligomers with Ga-coordination octahedra via common corners results in an overall three-dimensional framework which contains elliptical channels running along the [001] direction. The cross section of the channels is defined by eight-membered octahedral/tetrahedral rings (four Ga coordination octahedra, two phosphateand two borate-groups). Sodium ions are distributed within the open channels. The Ga—O bond distances are 1.925 and 1.965 A, while the Ga—OH value is increased to 1.995 A. The bond distances P—O and B—O in the oligomeric borophosphate groups correspond to respective values in the Feand Al-analogues [2,3]. Z. Kristallogr. NCS 216 (2001) 15–16 15 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless, prism, size 0.15 × 0.2 × 0.3 mm Wavelength: Mo K radiation (0.71073 A) : 45.94 cm Diffractometer, scan mode: Enraf Nonius CAD4, non-profiled scans 2 max: 69.86° N(hkl)measured, N(hkl)unique: 850, 737 Criterion for Iobs, N(hkl)gt: Iobs > 2 (Iobs), 676 N(param)refined: 75 Program: SHELXS-97 [4] Table 1. Data collection and handling. H(1) 4c 1/4 –1/4 1/2 0.05 H(2) 8f 0.485(7) 0.163(6) 0.591(7) 0.05 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso