A LAMELLAR HYDRATED BARIUM COBALT PHOSPHATE WITH A 2-DIMENSIONAL ARRAY OF CO-O-CO NETWORK - BA(COPO4)(2)CENTER-DOT-H2O

The hydrothermal synthesis and X-ray crystal structure of a hydrated b arium cobalt phosphate are presented, The structure is built from coba lt octahedra edge-shared with phosphorus tetrahedra, Cobalt polyhedra form corner-sharing chains along the crystallographic b axis, These ch ains are interconnected by water molecules and phosphate groups to for m an infinite two-dimensional sheet. Sheets are stacked along the crys tallographic c axis with charge balancing cations, Ba2+, located in th e interlayer region, The structure also consists of two-dimensional ar rays of Co-O-Co networks with cobalt centers forming hexagonal pattern s, There are a limited number of cobalt(II) phosphates in which the Co /P ratio is 1. A summary of these cobalt(II) phosphates is given, A cl assification scheme based on the extent of the Co-O-Co linkage is prov ided for cobalt phosphates. Crystal data for Ba(CoPO4)(2) . H2O, M = 4 63.16, space group C2 (No. 5), a = 9.2494(4) Angstrom, b = 4.9140(2) A ngstrom, c = 8.2650(4) Angstrom, beta = 91.744(2)degrees, V = 375.48(3 ) Angstrom(3), Z = 2, D-c = 4.097 g cm(-3), thin plate, MoK alpha, lam bda = 0.71073 Angstrom, mu = 10.005 mm(-1), 2 theta(max) = 56.44 degre es, R(F) = 2.43% for 70 parameters and 908 reflections with I > 2 sigm a(I). (C) 1997 Academic Press.