In this master’s thesis, the synthesis and comprehensive structural characterization of hybrid hexafluoridoferrate(III) systems with selected heterocyclic organic bases were investigated. Hexafluoridoferrates(III) represent an interesting class of coordination compounds in which the small and highly electronegative fluoride ligand stabilizes the metal center, enabling the formation of diverse supramolecular architectures. Despite several studies on fluoridometalates, the number of known crystal structures containing the hexafluoridoferrate anion [FeF$_6$]$^{3-}$ remains relatively limited. Therefore, the investigation of new systems is important for understanding the influence of the organic component on the organization of the crystal lattice.
In this work, selected pyridine bases and purine derivatives were used as organic components. Crystalline products were synthesized in hydrofluoric acid and thoroughly characterized using single-crystal X-ray diffraction (SCXRD), infrared (IR) and Raman spectroscopy, nuclear magnetic resonance spectroscopy ($^1$H and $^{19}$F NMR), powder X-ray diffraction (PXRD), as well as elemental and thermal analysis. In total, seven new compounds were structurally and spectroscopically characterized.
In most cases, the crystal structures contain isolated octahedral [FeF$_6$]$^{3-}$ units stabilized by an extensive network of hydrogen bonds of the N–H···F and O–H···F type, together with additional supramolecular interactions such as π–π interactions between aromatic rings. In one case, the formation of a polymeric Fe–F–Fe chain was observed. The results demonstrate that the choice of organic base and the synthesis conditions significantly influence the dimensionality, supramolecular organization, and stability of the resulting fluoridoferrate systems.
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