Tetrachloroferrate(III) Complexes Containing Some Heteroaromatic Organic Cations: Structures and Magnetic Properties

The crystal structures of tetrachloroferrate(III) complexes having stoichiometry (BH)+ [FeCl4]− (where B = isoquinoline and 4-aminopyridine) were determined at 100 K. While weak interactions, particularly N–H···Cl hydrogen bonds, are evident in the structures, distances between the Fe(III) centers are quite long in both cases. The structure of the compound with B = quinoline was compared with that previously established at room temperature, and showed that neither solid-solid nor magnetic phase transitions occurred in this temperature range. Magnetic measurements on the paramagnetic powders indicate weak antiferromagnetic interactions transmitted through the crystal lattice, giving rise to Néel temperatures that are significantly below 10 K. Comparisons are made with other characterized [FeCl4]− compounds having similar organic base cations, enabling clarification of the superexchange mechanism.