Redetermination of dipotassium trichlorido­stannate(II) chloride monohydrate

The title compound, K(2)[SnCl(3)]Cl·H(2)O, is the prototype of some isostructural compounds of composition M (2)[SnX (3)]X·H(2)O (M = large monovalent cation; X = halogen). In comparison with a previous study based on photographic data [Kamenar & Grdenić (1962 ▶). J. Inorg. Nucl. Chem. 24, 1039–1045], its crystal structure has now been redetermined using CCD-based data in order to gain more accurate values for bond lengths and angles within the [SnCl(3)](−) anion and to locate the H atoms. The [SnCl(3)](−) anion has a trigonal–pyramidal shape and exhibits crystallographic mirror symmetry. With the exception of the K(+) ion which is located on a general position, all other atoms are situated on crystallographic mirror planes. The coordination polyhedron of the cation may be described by means of nine atoms in the form of a monocapped square anti­prism with seven typical K—Cl/O distances and two additional atoms at considerably longer distances. The positions of the H atoms of the water mol­ecule (also lying on a crystallographic mirror plane) could be determined and confirm the existence of a bifurcated O—H⋯Cl hydrogen bond to neighbouring Cl atoms.