Two novel coordination compounds containing heterocyclic bidentate N,N-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)2(H2O)2](ClO4)2 (M = Fe(II) for (1) Co(II) for (2)). 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 1 and X-band EPR (Electron paramagnetic resonance), direct current (DC), and alternating current (AC) magnetic measurements in case of 2. The analysis of DC magnetic properties revealed a high spin arrangement in 1, significant rhombicity for both complexes, and large magnetic anisotropy in 2 (D = −21.2 cm−1). Moreover, 2 showed field-induced slow relaxation of the magnetization (Ueff = 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.

中文翻译：

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FeII 和 CoII 与 2-(furan-2-yl)-5-pyridin-2-yl-1,3,4-oxadiazole 配合物的结构和磁性性质

合成了两种含有杂环双齿 N,N-供体配体 2-(furan-2-yl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (fpo) 的新型配位化合物。源自铁、钴和 fpo 的高氯酸盐的化合物的通式可写为： [M(fpo)2(H2O)2](ClO4)2 (M = Fe(II) for (1) Co(II))对于（2））。化合物的表征通过一般的物理化学方法进行——元素分析 (EA)、傅里叶变换红外光谱 (FT-IR)、有机物的核磁共振 (NMR) 和单晶 X 射线衍射 (sXRD) . 此外，还使用静态场 (DC) 测量 1 和 X 波段 EPR（电子顺磁共振）、直流 (DC) 和交流 (AC) 磁测量（在 2 的情况下）研究了磁化学特性。直流磁特性的分析揭示了 1 中的高自旋排列，两种配合物的显着菱形，以及 2 中的大磁各向异性（D = -21.2 cm-1）。此外，2 显示出磁场诱导的磁化缓慢弛豫（Ueff = 65.3 K）。EPR 光谱和从头计算 (CASSCF/NEVPT2) 证实了易轴各向异性的存在和第二个配位球的重要性。