Crystal structure of potassium indium (monophosphate-hydrogenmonoborate- monophosphate), KIn[BP2O8(OH)

Abstract

BHInKO9P2, triclinic, P1 (No. 2), a = 5.2638(4) A, b = 8.4791(5) A, c = 8.1469(9) A, = 91.741(7)°, = 93.061(7)°, = 79.823(5)°, V = 357.3 A, Z = 2, Rgt(F) = 0.052, wRref(F) = 0.113, T = 293 K. Source of material KIn[BP2O8(OH)] was synthesized under mild hydrothermal conditions. The reactions were carried out with mixtures of In metal (0.057 g) dissolved in 1 ml of HCl (18%), H3BO3 (0.062 g) and K2HPO4 (0.522 g) (molar ratio of In:P:B = 1:2:3) in aqueous solution. The mixtures were sealed in glass tubes (after adding 1 ml H2O to achieve a degree of filling of 30%) with subsequent heating at 418 K for 14 days. The starting materials were all of analytical purity grade. Discussion With the increasing interest in microporous materials, the syntheses of compounds like borophosphates with open framework structures 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 two compounds with Al and Ga [2,3] reported only recently and two phases with In in the present issue [4,5]. The structure of the title compound is isotypic to the K-Fe [6] and ammonium-In analogues [5]. The structure is characterized by isolated InO5(OH) octahedra sharing common O-corners with phosphate and common O(OH)-corner with hydrogenborate groups from the trinuclear oligomeric units [B2P4O16(OH)2]. The condensation of the borophosphate oligomers with In-coordination octahedra via common corners results in a three-dimensional framework which contains elliptical channels running along the a axis. The cross section of the channels is defined by eight-membered octahedral/tetrahedral rings (two In coordination octahedra, four phosphateand two borate-groups). Potassium ions are distributed within the open channels. The In—O and In—OH bond distances range from 2.110 A to 2.179 A. Both the oligomeric borophosphate and the coordination octahedron of In are similar to its K-Feand NH4-In-analogues [5,6] by considering the bond distances In—O, P—O and B—O and bond angles. Z. Kristallogr. NCS 217 (2002) 3–4 3 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless prism, size 0.2 × 0.25 × 0.3 mm Wavelength: Mo K radiation (0.71073 A) : 44.09 cm Diffractometer, scan mode: Enraf Nonius CAD4, /2 2 max: 68.04° N(hkl)measured, N(hkl)unique: 3081, 2910 Criterion for Iobs, N(hkl)gt: Iobs > 2 (Iobs), 2126 N(param)refined: 131 Program: SHELXL-97 [7] Table 1. Data collection and handling. H(1) 2i 0.68(2) 0.51(1) 0.64(1) 0.05 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso