THE CRYSTAL-STRUCTURE OF MONOCLINIC AG5CU3(PO4)2((PO4)H(PO4)) AND ITS RELATIONSHIP TO THE TRICLINIC SODIUM ANALOG

The crystal structure of Ag5Cu3(PO4)2[(PO4)H(PO4)] was determined from 2611 single crystal X-ray data [a = 17.725(6) angstrom, b = 5.162(2) angstrom, c = 8.584(6) angstrom, beta = 125.66(2)-degrees, space group C2/c, Z = 4, R(w) = 0.032, sin-theta/lambda less-than-or-equal-to 0.80 angstrom-1]. (One part of the PO4 tetrahedra form dimers via a symmetrically restricted, very short O-H-O bond of 2.428(6) angstrom). Simultaneously this hydrogen bond is a common edge between two coordination polyhedra of Ag atoms. The Cu(1) atom is in a square planar [4] environment. The Cu(2) atom is tetragonal pyramidal [5] coordinated with an uncommon distribution of Cu-O bond lengths [1.933(2), 1.934(2), 1.976(2), 2.105(2) and 2.180(2) angstrom]. Monoclinic Ag5Cu3(PO4)2[(PO4)H(PO4)] has topologically the same [Cu3(PO4)4]2- layers as triclinic Na5Cu3(XO4)2[(XO4)H-(XO4)] (X=P, As), but a different stacking sequence. In both cases these layers are connected by hydrogen bonds and by Na and Ag atoms, respectively, to a three-dimensional network structure.