NaZn(H2O)(2)[BP2O8]center dot H2O: A novel open-framework borophosphate and its reversible dehydration to microporous sodium zincoborophosphate Na[ZnBP2O8]center dot H2O with CZP topology

Crystals of NaZn(H2O)(2)[BP2O8]. H2O were grown under mild hydrothermal con ditions at 170 degrees C. The crystal structure (solved by X-ray single-cry stal methods: hexagonal. P6(1)22 (no. 178). a = 946.2(2). c = 158.3.5(1) pm . V = 1227.8(4) 10(6) pm(3). Z = 6) exhibits a chiral octahedral-tetrahedra l framework related to the CZP topology and contains helical ribbons of cor ner-linked berate and phosphate tetrahedra. Investigation of the thermal be havior up to 180 degrees C shows a (reversible) dehydration process: this l eads to the microporous compound Na[ZnBP2O8].H2O. which has the CZP topolog y. The crystal structure of Na[ZnBP2O8].H2O was determined by X-ray powder diffraction by using a combination of simulated annealing, lattice-energy m inization, and Rietveld refinement procedures (hexagonal, P6(1)22 (no. 178) , a = 954.04(2), c = 1477.80(3) pm, V = 1164.88(5) . 106 pm(3), Z = 6). The essential structural difference caused by the dehydration concerns the coo rdination of Zn3+ changing from octahedral to tetrahedral arrangement.