Synthesis and characterization of a new family of thermally stable open-framework zincophosphate/arsenate phases: M(3)Zn(4)O(XO(4))(3)center dot nH(2)O (M=Na, K, Rb, Li, ...; X=P, As; n=similar to 3.5-6). Crystal structures of Rb3Zn4O(PO4)(3)center dot 3.5H(2)O, K3Zn4O(AsO4)(3)center dot 4H(2)O, and Na3Zn4O(PO4)(3)center dot 6H(2)O

The syntheses, representative crystal structures, and some properties of a new family of microporous zincophosphate/arsenate materials, denoted M(3)Zn(4)O(XO(4))(3) . nH(2)O (M = Li, Na, K, Rb, Cs,...; X = P, As; n = similar to 3.5-6), are reported. All these materials are based on a flexible, anionic Zn4O(XO(4))(3) network built up from vertex-linked tetrahedral ZnO4 and XO(4) units. Four ZnO4 units share a vertex, resulting in novel OZn4 centers. The use of mixed four-coordinate anion types (XO(4)(3-), O2-) results in a number of interesting structural and stability properties. The M(3)Zn(4)O(XO(4))(3) . nH(2)O network contains only pairs of 3-rings (a spiro-5 unit) and 8-rings, and no 4-rings or 6-rings: it encloses roughly spherical cavities connected by a three-dimensional network of 8-ring channels propagating in the orthogonal [100], [010], and [001] directions (cubic unit-cell axes). Extraframework cations and water molecules occupy these cavities and channels. These phases display typical ''zeolitic'' dehydration/ rehydration and ion-exchange reactions with thermal stabilities up to 600 degrees C, the highest known for this type of open-framework Zn(P/As)O material. The included guest cation (Na, Rb, K, Li,...) has a crucial effect on crystal structure, by ordering in and modifying the configuration of the intercavity 8-ring channels. The crystal structures of Rb3Zn4O(PO4)(3) . 3.5H(2)O, K3Zn4O(AsO4)(3) . 4H(2)O, and Na3Zn4O(PO4)(3) . 6H(2)O are presented. Crystal data: Rb3Zn4O(PO4)(3) Zn4O(PO4)(3) . 3.5H(2)O, M(r) = 881.40, cubic, space group <F(4)over bar 3c> (No. 219), a = 15.3423(9) Angstrom, V = 3611.4(6) Angstrom(3), Z = 8, R(p) = 5.12%, R(wp) = 6.78%, 27 parameters, 1874 data points (X-ray Rietveld refinement): K3Zn4O(AsO4)(3) . 4H(2)O M(r) = 883.63, cubic, space group <F(4)over bar 3c> (No. 219), a = 15.4638(2) Angstrom, V = 3697.9(2) Angstrom(3), Z = 8, R(p) = 8.69%, R(wp) = 11.42%, 24 parameters, 2124 data points (X-ray Rietveld refinement). Na3Zn4O(PO4)(3) 6H(2)O, M(r) = 739.49, trigonal, space group R3c (No. 161), a = 10.7489(3) Angstrom, alpha = 60.114(2)degrees, V = 880.4(4) Angstrom(3), Z = 2, R = 2.49%, R(w) = 2.61%, 180 parameters, 846 observed reflections with I > 3 sigma(I) (single-crystal data).