1. Slow magnetic relaxation in dinuclear Co(III)–Co(II) complexes containing a five-coordinated Co(II) centre with easy-axis anisotropy.
- Author
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Liu, Mengyao, Yang, Yimou, Jing, Rong, Zheng, Shaojun, Yuan, Aihua, Wang, Zhenxing, Luo, Shu-Chang, Liu, Xiangyu, Cui, Hui-Hui, Ouyang, Zhong-Wen, and Chen, Lei
- Subjects
MAGNETIC relaxation ,MAGNETIC anisotropy ,SINGLE molecule magnets ,ELECTRON paramagnetic resonance ,MAGNETIC measurements ,MAGNETIC susceptibility - Abstract
Two air-stable Co(III)–Co(II) mixed-valence complexes of molecular formulas [Co
II CoIII (L)(DMAP)3 (CH3 COO)]·H2 O·CH3 OH (1) and [CoII CoIII (L)(4-Pyrrol)3 (CH3 COO)]·0.5CH2 Cl2 (2) (H4 L = 1,3-bis-(5-methyl pyrazole-3-carboxamide) propane; DMAP = 4-dimethylaminopyridine; and 4-Pyrrol = 4-pyrrolidinopyridine) were synthesized and characterized by single-crystal X-ray crystallography, high-field electron paramagnetic resonance (HFEPR) spectroscopy, and magnetic measurements. Both complexes possess one five-coordinated paramagnetic Co(II) ion and one six-coordinated Co(III) ion with octahedral geometry. Direct-current magnetic susceptibility and magnetization measurements show the easy-axis magnetic anisotropy that is also confirmed by low-temperature HFEPR measurements and theoretical calculations. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal their field-assisted slow magnetic relaxation, which is a characteristic behavior of single-molecule magnets (SMMs), caused by the individual Co(II) ion. The effective energy barrier of complex 1 (49.2 cm−1 ) is significantly higher than those of the other dinuclear Co(III)–Co(II) SMMs. This work hence presents the first instance of the dinuclear Co(III)–Co(II) single-molecule magnets with a five-coordinated environment around the Co(II) ion. [ABSTRACT FROM AUTHOR]- Published
- 2022
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