Crystal Structure, Charge-Transfer-Induced Spin Transition, and Photoreversible Magnetism in a Cyano-Bridged Cobalt−Tungstate Bimetallic Assembly
| Autor: | Hiroko Tokoro, Tomoyuki Matsuda, Yoshihide Tsunobuchi, Shin-ichi Ohkoshi, Yoshiho Hamada |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Chemistry of Materials. 20:3048-3054 |
| ISSN: | 1520-5002 0897-4756 |
| DOI: | 10.1021/cm703258n |
| Popis: | This paper describes the crystal structure, magnetic properties, and photoreversible magnetic properties of CoII3[WV(CN)8]2(pyrimidine)4·6H2O. We found that complexes of this formula had two types of crystal structures ([{CoII(pyrimidine)2}2{CoII(H2O)2}{WV(CN)8}2]·4H2O (1) and [{CoII(pyrimidine)(H2O)}2{CoII(H2O)2}{WV(CN)8}2](pyrimidine)2·2H2O (2)). These two structures had similar metal−organic frameworks but differed in the coordination environment around Co1, i.e., Co1(NC)4(pyrimidine)2 in 1 and Co1(NC)4(pyrimidine)(H2O) in 2. In 1, a temperature-induced phase transition from the CoII (S = 3/2)−NC−WV (S = 1/2) [high-temperature (HT)] phase to the CoIII (S = 0)−NC−WIV (S = 0) [low-temperature (LT)] phase was observed due to a charge-transfer-induced spin transition. However, 2 did not exhibit such a phase transition. When the LT phase of 1 was irradiated by 840 nm light, ferromagnetism with a Curie temperature of 40 K and magnetic coercive field of 12 kOe were observed. UV–vis reflectance and infrared me... |
| Databáze: | OpenAIRE |
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