STRUCTURE OF TRIAMMONIUM HEXAHYDROGENHEXAMOLYBDORHODATE(III) HEXAHYDRATE

(NH4)3[H6RhMo6O24].6H2O, M(r) = 1230.79, monoclinic, P2(1)/c, a = 11.435 (3), b = 11.017 (2), c = 11.789 (2) angstrom, beta = 100.02 (2)degrees, V = 1462.6 (6) angstrom3, Z = 2, D(m) = 2.83, D(x) = 2.79 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 3.08 mm-1, F(000) = 1176, T = 296 K, final R = 0.042 for 2248 observed reflections with \F0\ > 3.0-sigma(\F0\). The [H6RhMo6O24]3- polyanion, which has approximate D3d symmetry, is isostructural to [H6Cr(III)Mo6O24]3-. The RhO6 octahedron located on an inversion center is trigonally distorted with the Rh-O distances in the range 2.019 (5)-2.030 (5) angstrom. The Mo-O distances are in the range 1.701 (7)-2.298 (5) angstrom.