Crystal Engineering through Face Interactions between Tetrahedral and Octahedral Building Blocks:  Crystal Structure of [ε-Al13O4(OH)24(H2O)12]2[V2W4O19]3(OH)2·27H2O

A new intercluster salt crystal [ε-Al13O4(OH)24(H2O)12]2[V2W4O19]3(OH)2·27H2O (1) was synthesized from the reaction of octahedral Lindqvist-type polyoxometalate [V2W4O19]4- and truncated tetrahedral Keggin-type [ε-Al13O4(OH)24(H2O)12]7+ cluster ions. The crystal structure shows that the oppositely charged cluster ions are arranged alternately and have their contacting faces parallel to each other for maximal interactions, both electrostatic and hydrogen bonding. The face-to-face interaction mode of the clusters allows analysis of the crystal structure in an analogy to the bond directionality of conventional inorganic crystals. Therefore, the packing of clusters in 1 is that of As2O3 (Claudetite-II). With the bond directionality, the crystal has large one-dimensional channels with a cross-sectional area of 14.17 × 13.88 Å2 that are filled by lattice water and charge-balancing OH-.