PREPARATION AND CRYSTAL-STRUCTURE OF NA2ZN(HPO4)2.4H2O, A NEW LAYERED SODIUM ZINC PHOSPHATE-CONTAINING BIFURCATED TETRAHEDRAL 12-RINGS

We report the low-temperature (approximately 0-degree-C) synthesis and X-ray single-crystal structure of Na2Zn(HPO4).4H2O, a new layered material, whose structure is built up from sheets of vertex-sharing ZnO4 and HPO4 tetrahedra, which encapsulate octahedrally coordinated ''guest'' sodium cations and water molecules. The Zn/P tetrahedral-atom connectivity in Na2Zn(HPO4)2.4H2O results in a two-dimensional network of layers of ''bifurcated,'' tetrahedral 12-rings, with interlayer connectivity established only by sodium cations and via H bonds. X-ray powder data and P-31 MAS NMR spectra are consistent with those expected from the crystal structure data. Crystal data are Na2Zn(HPO4)2.4H2O (ZnNa2P2O12H10), M(r) = 375.37, monoclinic, space group P2(1)/c(No. 14), a = 8.947(2) angstrom, b = 13.254(2) angstrom, c = 10.098(2) angstrom, beta = 116.358(6)-degrees, V = 1074.5 angstrom-3, Z = 4, R = 4.25%, and R(w) = 5.68% [1608 unique reflections with I > 3 sigma(I)]. (C) 1994 Academic Press, Inc.