Field-induced slow magnetic relaxation in mixed valence di- and tri-nuclear CoII–CoIII complexes
| Autor: | Aparup Paul, Subal Chandra Manna, Joan Cano, Horst Puschmann, Marta Viciano-Chumillas |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Dalton Transactions. 49:9516-9528 |
| ISSN: | 1477-9234 1477-9226 |
| DOI: | 10.1039/d0dt00588f |
| Popis: | Two novel mixed valence CoII–CoIII complexes, namely [CoIICoIII(L1)(ab)(mb)2(H2O)]·dmf (1) and [CoIII2CoII(L2)4(H2O)4]·2H2O (2) [H2L1 = (E)-2-((1-hydroxybutan-2-ylimino)methyl)-6-methoxyphenol, ab = 2-amino-butan-1-ol anion, mb = p-methyl benzoate, H2L2 = 3-((2-hydroxy-3-methoxy-benzylidene)-amino)-propionic acid, and dmf = N,N-dimethyl-formamide], were synthesized and characterized by single crystal X-ray diffraction and magnetic studies at low temperature. The structure determination reveals that both complexes belong to the monoclinic system with P21/c (1) and I2/a (2) space groups. Complex 1 is a dinuclear CoIIICoII compound with distorted octahedral cobalt centers showing different coordination environments. In 2, a bent trinuclear CoIII2CoII complex, the coordination environments around the two terminal CoIII sites are alike, whereas they are different in the central CoII ion. Alternating current/direct current (ac/dc) magnetic studies revealed that both complexes show field-induced slow magnetic relaxation. The dc magnetic susceptibility and magnetization data were analyzed with the following Hamiltonianwhere D and E are the axial and rhombic zero-field splitting (zfs) parameters, respectively, and a good agreement between experimental and simulated results was found using the parameters g⊥ = 2.585, g∥ = 2.437, D = +98.1 cm−1, E/D = 0.008 and F = 8.2× 10−5 for 1 and g⊥ = 2.580, g∥ = 2.580, D = +55.4 cm−1, and E/D = 0.000 for 2. |
| Databáze: | OpenAIRE |
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