The Structural and Magnetic Properties of Fe II and Co II Complexes with 2-(furan-2-yl)-5-pyridin-2-yl-1,3,4-oxadiazole

• Published in: Molecules (Basel, Switzerland) Vol. 25; no. 2
• Main Authors: Zoufalý, Pavel, Čižmár, Erik, Kuchár, Juraj, Herchel, Radovan
• Format: Journal Article
• Language: English
• Published: Switzerland 09.01.2020
• Subjects: second coordination sphere; 1,3,4-oxadiazole; single-molecule magnet
• ISSN: 1420-3049
• DOI: 10.3390/molecules25020277

Two novel coordination compounds containing heterocyclic bidentate , -donor ligand 2-(furan-2-yl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (fpo) were synthesized. A general formula for compounds originating from perchlorates of iron, cobalt, and fpo can be written as: [M(fpo) (H O) ](ClO ) (M = Fe(II) for ( ) Co(II) for ( )). The characterization of compounds was performed by general physico-chemical methods-elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) in case of organics, and single crystal X-ray diffraction (sXRD). Moreover, magneto-chemical properties were studied employing measurements in static field (DC) for and X-band EPR (Electron paramagnetic resonance), direct current (DC), and alternating current (AC) magnetic measurements in case of . The analysis of DC magnetic properties revealed a high spin arrangement in , significant rhombicity for both complexes, and large magnetic anisotropy in ( = -21.2 cm ). Moreover, showed field-induced slow relaxation of the magnetization ( = 65.3 K). EPR spectroscopy and ab initio calculations (CASSCF/NEVPT2) confirmed the presence of easy axis anisotropy and the importance of the second coordination sphere.