Influence of the charge of the complex unit on the SCO properties in pyrazolyl-pyridinyl-benzimidazole based Fe(II) complexes

• Published in: Polyhedron 2017-10, Vol.135, p.189-194
• Main Authors: Rajnák, C., Schäfer, B., Šalitroš, I., Fuhr, O., Ruben, M., Boča, R.
• Format: Article
• Language: English
• Subjects: Crystal structure; Fe(II) complex; LIESST effect; Magnetic measurements; Spin crossover
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2017.06.035

We have prepared the ionic and charge-neutral complexes [Fe(pzpybzim)2](BF4)2 and [Fe(pzpybzim-1H)2] of the basic 2-(6-pyrazol-1-yl-pyridin-2-yl)-1H-benzimidazole (pzpybzim) ligand. Reactions of this ligand with Fe(II) ion gave a set of hexacoordinate complexes showing thermally induced spin crossover with the critical temperature lying above the room temperature. Furthermore, the photomagnetic investigation confirmed the LIESST effect for both compounds. [Display omitted] A tridentate ligand 2-(6-pyrazol-1-yl-pyridin-2-yl)-1H-benzimidazole (L1H) has been synthesized and characterized by NMR, UV–Vis, IR and MS spectroscopy. Starting from L1H, two complexes have been prepared, one containing a complex dication counterbalanced by anions, [Fe(L1H)2](BF4)2 (1), and the other one is a charge neutral complex [Fe(L1)2] (2). The distorted octahedral coordination of 1 was confirmed by X-ray diffraction analysis. Both complexes show a thermally induced spin crossover with the critical temperature lying above the room temperature. The photomagnetic investigation confirmed the LIESST effect for both compounds.