Metal–organic hybrids involving the [UO 2 Cl 3 (NO 3 )] 2− tecton and the role of halogen polarizability

The reaction of uranyl nitrate hexahydrate with 4-halopyridinium ions (X = Cl, Br, I) in high chloride media has resulted in three novel compounds, each of which is based around the [UO2Cl3(NO3)]2− tecton; (C5H5NCl)2[UO2Cl3(NO3)], (C5H5NBr)2[UO2Cl3(NO3)] and (C5H5NI)3[UO2Cl3(NO3)](NO3). In each material the halogen is involved in various forms of intermolecular interaction, including hydrogen bonding, halogen–halogen interactions and halogen–nitrate interactions. Presented is a discussion of the role of the halogen, in terms of Lewis acidity, in directing the overall structure.