SYNTHESIS, STRUCTURE AND MAGNETIC MEASUREMENT OF A NEW LAYERED COPPERHYDROGENSELENITE - [CU(HSEO3)(2)]CENTER-DOT(NH4)CL

The crystal structure of a new compound of copper layered hydrogensele nite [Cu(HSeO3)(2)] . (NH4)Cl has been determined. This compound cryst allizes in the orthorhombic system, space group Pnma, with a = 8.975(2 ), b = 12.118(2), c = 7.265(1) Angstrom, Z = 4 and V = 790.1(2) Angstr om(3). This structure is mainly two-dimensional; copper atoms bridged by HSeO3- anions build layers parallel to (010). The sheets are simila r to those obtained for Cu(HSeO3)(2). The copper atom presents a class ical environment, elongated tetragonal bipyramid, with four oxygen ato ms belonging to four HSeO3- groups and two chloride ions. The chloride ions bridge two copper atoms belonging to neighboring layers. The amm onium ions, localized into the interlayer space, are related to the la ttice by hydrogen bonds. Magnetic measurements of this compound reveal the occurrence of weak ferromagnetism at low temperature.