Hydroxocentered [(OH)Tl3]2+ triangle as a building unit in thallium compounds: synthesis and crystal structure of Tl4(OH)2CO3

Abstract

Abstract The new thallium hydroxocarbonate Tl4(OH)2CO3 has been obtained by evaporation from aqueous solution. The crystal structure of the compound has been solved by direct methods: orthorhombic, Cmc21, a = 8.9963(18), b = 12.1500(30), c = 7.9542(15) Å, V = 869.43(3) Å3, R 1 = 0.056 for 763 unique reflections with |F o| ≥ 4σ F. There are three symmetrically independent Tl+ cations in the structure. The O atoms of the OH- groups are triangularly coordinated by three Tl atoms that results in formation of OHTl3 triangles with the O atom located at approx. 1.00 Å above the Tl3 plane. The OH- centered units are connected via common edges into [OH2Tl4]2+ dimers linked into chains through Tl–O bonds to CO3 groups. The structure contains channels parallel to the c axis. The formation of the lone pair cavity causes repulsion of Tl+ cations across these cavities and, as a consequence, distortion of the Tl+ cation arrangement.