Synthesis and crystal structures of two inorganic–organic hybrid vanadium selenites with layered structures: (DABCOH2)[(VO2)(SeO3)]2·1.25H2O and (pipeH2)[(VO)2(C2O4)(SeO3)2]

The reactions of SeO2 with V2O5 or VOSO4 in the presence of different organic amine yield two novel vanadium selenites with layered structures, formulated as (DABCOH2)[(VO2)(SeO3)]2·1.25H2O 1 (DABCO = 1,4-diazabicyclooctane) and (pipeH2)[(VO)2(C2O4)(SeO3)2] 2 (pipe = piperazidine). Two compounds are characterized with elemental analysis, FT-IR spectrum, TG-DTA analysis and single-crystal X-ray diffraction analysis. In compound 1, two symmetry-related VO6 units share an edge to form a [V2O6] cluster. Each [V2O6] cluster is bridged by four SeO3 units to generate a two-dimensional grid structure. In compound 2, VO6 units and SeO3 units share corners to result in a ladder motif. Adjacent chains are interlinked by the oxalate ligands, creating a 2D brick-wall structure, which is firstly observed in V/Se/O system. Diprotonated DABCO and lattice water molecules in 1 and diprotonated piperazidine molecules in 2 are located in the interlayer regions and interact with the framework oxygen atoms via hydrogen bonds, respectively.