The Halogen Effect on the Magnetic Behaviour of Dimethylformamide Solvates in [Fe(halide-salEen)2]BPh4

Complexes [Fe(X-salEen)2]BPh4·DMF, with X = Br (1), Cl (2), and F (3), were crystallised from N,N′-dimethylformamide the aim of understanding role a high boiling point solvate in spin crossover phenomenon. The counter ion was chosen for only being able to participate weak intermolecular interactions. compounds structurally characterised by single crystal X-ray diffraction. Complex 1 orthorhombic space group P212121, complexes 2 3 monoclinic P21/n. Even at room temperature, low predominant form, although complex exhibited largest proportion high-spin species according both magnetisation measurements Mössbauer spectra. Density Functional Theory calculations performed on periodic solids molecular models 1–3 iodide analogue 4. While all approaches reproduced experimental structures very well, energy balance between low-spin forms harder reproduce, though some pointed easier 2, as observed. Periodic functional PBE led similar ΔEHS-LS values but showed preference form. However, single-point B3LYP* showed, model without solvate, that should undergo more easily. also reflected this fact, which clearly defined when cation–anion–solvate used. In other there not much difference Cl, Br, I complexes.