Reinvestigation of Sr2[Cu(OH)6]

During an investigation of the SrO-CuO-P2O5-H2O system, single crystals of distrontium hexahydroxidocuprate(II), Sr-2-[Cu(OH)(6)], were obtained by the hydrothermal method. The blue prismatic crystals of Sr-2[Cu(OH)(6)] adopt the same structure type as Ba-2[Cu(OH)(6)], Sr-2[Zn(OH)(6)] and Ba-2[Zn(OH)(6)]. The Cu atoms, located at (0, 0, 1 2) (site symmetry 1), form mutually isolated and highly elongated Cu(OH)(6) octahedra, which are interconnected to slightly distorted Sr(OH)(6) trigonal prisms, forming a layered structure. The location of H atoms from difference Fourier maps and their refinement allowed the precise determination of a three-dimensional hydrogen-bonding network in which all hydroxide O atoms are involved. In addition, the hydrogen-bonding topologies in Sr-2[Cu(OH)(6)] and other similar hexahydroxidometallates with the general formulae M1[M2(OH)(6)], M1(2)[M2-(OH)(6)] and M1(3)[M2(OH)(6)] were analysed in detail.