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 [Cr 3 O(H 2 O) 3 (OOCH) 6 ] 2 [P 2 W 18 O 62 ] · 9.5H 2 O( 1 ) and K 4 [Cr 3 O(H 2 O) 3 · (OOCH) 6 ] [H 3 P 2 W 17 Co(H 2 O) 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 K 4 Cr 6 P 2 W 18 ( 1 ), hexagonal P 6 (3)/ m, a = 1.5895 (2) nm, b = 1.5895(2) nm, c = 2.1620 (4) nm, α = 90°, β = 90°, γ = 120°, V = 4.7305 (13) nm 3 , Z = 2, R 1 = 0.0726, wR 2 = 0.1542; C 6 H 57 O 98 K 4 Cr 3 CoP 2 W 17 ( 2 ), hexagonal P 6(3)/ mmc, a = 1.61328(3) nm, b = 1.61328(3) nm, c = 2.06613(9) nm, α = 90°, β = 90°, γ = 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 °C, whereas crystal 2 lost the water of crystallization at 100 °C. 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.