ND2(OH)2(CRO4)2 AND [TB2(CRO4)3(H2O)5]CENTER-DOT-2H2O

The structures of neodymium hydroxide chromate and pentaaquaterbium(III) chromate dihydrate have been determined. Two kinds of Nd atoms, with different environments, are present in the structure of Nd2(OH)2(CrO4)2. The coordination polyhedron of the eight O atoms around the Nd atoms is a square antiprism. In [Tb2(CrO4)3(H2O)5].2H2O, the Tb atoms are nine-coordinated and are located in two types of site. The coordination polyhedra consist of both a tricapped trigonal prism and a monocapped square antiprism. In the two title compounds the CrO4 groups are nearly regular tetrahedra, having mean Cr-O distances of 1.651(7) and 1.650(7) angstrom for Nd2(OH)2(CrO4)2 and [Tb2(CrO4)3(H2O)5].2H2O, respectively.