Iron-containing ionic liquid crystals of N,N'-dialkylimidazolium salts ([(CnH2n+1)(2)IM](3)[Fe(CN)(6)], with n = 12 (1), 14 (2), 16 (3), 18 (4), IM = imidazolium) were prepared and their structures and properties were characterized. Differential scanning calorimetry (DSC), polarizing optical microscopy (POM) as well as powder X-ray diffraction (PXRD) analysis reveal for all compounds thermotropic liquid crystalline behavior. The observed textures point to smectic A and smectic X phases. The crystal structure of the solvate [C12C12IM](3)[Fe(CN)(6)].2 DMSO (DMSO = dimethylsulfoxide) was examined by single crystal X-ray diffraction analysis which reveals two crystallographically independent [ C12C12IM](+) cations with different conformation, U-shape and rod-shape, together with a nearly ideal octahedral [Fe(CN)(6)](3-) anion and two DMSO solvent molecules. The crystal packing is characterized by alternating bilayers of almost linearly arranged imidazolium cations with the U-shaped cations being arranged in a head-to-head fashion and the cations' hydrophobic dodecyl chains being interdigitated. Magnetic measurements for compounds 1-4 show paramagnetic moments, mu(eff), of similar to 1.7 mu(B), which are close to the theoretically expected value for a d(5) low-spin Fe3+ spin-only S = 1/2 system (mu(s.o.)(eff) = 1.73 mu(B)). It was possible to obtain an Fe3+ containing ILC material that combines liquid crystalline behavior over a large mesophase window (from 33 degrees C to 170 degrees C) with high magnetic susceptibility by mixing compound 3 with [C16C16IM][FeCl4] (5), which contains the d(5) high-spin Fe3+ ion (S = 5/2). All compounds are highly hydrophobic and stable in the atmosphere indicating a great potential of applications as functional materials.