STRUCTURE OF MGCL2.RBCL.6H2O

Magnesium rubidium trichloride hexahydrate, M(r) = 324.22, triclinic, Pl, a = 6.672 (5), b = 13.282 (15), c = 6.639 (5) angstrom, alpha = 89.83 (8), beta = 91.72 (6), gamma = 90.41 (8)-degrees, V = 588.0 (14) angstrom 3, Z = 2, D(x) = 1.831 Mg m-3, lambdaBAR(Mo K-alpha) = 0.71073 angstrom, mu = 5.17 mm-1, F(000) = 320, T = 253 K, R(F) = 0.078 for 2604 independent reflections with \F(o)\ > 3-sigma(\F(o)\). The crystal consists of a network of top-sharing [RbCl6] octahedra and isolated [Mg(H2O)6]2+ octahedra occupying holes in the [RbCl6] network. Rb+ ions are coordinated with six Cl- ions and each Cl- ion is surrounded by two Rb+ ions and four O atoms of water molecules. The Mg-O bond length varies from 1.982 (14) to 2.115 (13) angstrom in the [Mg(H2O)6)2+ octahedron. Each H2O molecule is hydrogen bonded to two Cl- ions.