Syntheses, crystal structures and characterization of two zeotype crystals of K4[Cr3O(H2O)3(OOCH)6]2[P2W18O62] • 9.5H2O and K4[Cr3O(H2O)3(OOCH)6] • [H3P2W17Co(H2O)O61] • 20H2O

Two novel zeotype crystals, K-4[Cr3O(H2O)(3)(OOCH)(6)](2)[P2W18O62] (.) 9.5H(2)O(1) and K-4[Cr3O(H2O)(3) (.) (OOCH) (6)][H3P2W17Co(H2O)O-61] (.) 20H(2)O (2), were synthesized and their structures were determined using X-ray single crystal diffraction. Crystal data: C-12 H-43 O-103.5 K4Cr6P2 W-18 (1) hexagonal P6(3)/m, a = 1.5895 (2) nm, b = 1.5895 (2) nm, c = 2.1620 (4) nm, alpha = 90 degrees, beta = 90 degrees, gamma = 120 degrees, V = 4. 7305 (13) nm(3), Z = 2, R-1 = 0.0726, wR(2) 0.1542; C6H57O18K4Cr3 CoP2 W-17 (2), hexagonal P6 (3)/mmc, a = 1. 61328 (3) nm, b = 1 61328 (3) nm, c = 2. 06613 (9) nm, alpha = 90 degrees, beta = 90 degrees, gamma = 120', V = 4. 6570 (2) nm(3), Z = 2, R-1 = 0.0377, wR(2) =0.1070. These crystals were characterized using elemental analysis, IR, TG-DTA, and XRD. It was found that the polyoxometalate anions maintained Wells-Dawson structure for crystal 1 and lacunary Wells-Dawson structure for crystal 2. Thermal analysis showed that crystal 1 lost the water of crystallization at 132 degrees C, whereas crystal 2 lost the water of crystallization at 100 T. Crystal 1 could reversibly desorb and adsorb water molecules and its crystal structure could be restored after re-adsorbing the water molecules. It was also found from the XRD patterns that the void size of crystal 2 is smaller compared with that of crystal 1, which is attributed to the higher anion charges.