Pentapotassium dodecatungstoborate(III) hexadecahydrate

The title compound, K-5[BW12O40]. 16H(2)O, contains a [BW12O40](5-) polyani on of 222 crystallographic symmetry, with a central tetrahedrally coordinat ed B-III atom surrounded by four groups of three edge-sharing octahedra (W3 O13 subunits), which are linked in turn to each other and to the central BO 4 tetrahedron by shared O atoms at the vertices. There is a crystallographi cally unique B-O bond of 1.554 (10) Angstrom, while the average W-O distanc es are 2.344 (17) Angstrom for four coordinate O atoms, 1.917 (12) and 1.89 (2) Angstrom for two coordinate O atoms within and connecting the W3O13 su bunits, respectively, and 1.709 (8) Angstrom for terminal O atoms. Not all of the K+ ions and H2O groups were located.