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Gran barrera de anisotropía en un imán tetranuclear de una sola molécula con centros de cobalto de baja coordenada
Khetpakorn Chakarawet, Philip C Bunting, Jeffrey R Long1
1Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
Journal of the American Chemical Society
|January 24, 2018
Resumen
Este estudio sintetizó un compuesto de cluster de cobalto que exhibe un estado de alto espín estable y una relajación magnética lenta. Esta investigación destaca el acoplamiento de centros metálicos de baja coordinación como una estrategia para mejorar la anisotropía magnética en grupos de metales de transición.
Área de la Ciencia:
- Química inorgánica
- Ciencias de los materiales
- Magnetoquímica
Sus antecedentes:
- Los centros metálicos de baja coordenada en los grupos de metales de transición son cruciales para las propiedades magnéticas únicas.
- Comprender la comunicación electrónica entre los centros metálicos es clave para controlar la relajación magnética.
Objetivo del estudio:
- Para sintetizar y caracterizar un compuesto de cobalto tetranuclear.
- Investigar el efecto de la comunicación electrónica en la relajación magnética lenta.
- Explorar estrategias para mejorar la anisotropía magnética en grupos de metales de transición.
Principales métodos:
- Oxidación química de Co4 ((NPtBu3) 4) mediante el uso de [FeCp2] [B ((C6F5) 4].
- Caracterización magnética mediante mediciones de la susceptibilidad magnética dc y ac.
- Análisis de la dinámica de relajación magnética a través de procesos Orbach, túnel cuántico y Raman.
Principales resultados:
- El compuesto sintetizado [Co4 ((μ-NPtBu3) 4] [B ((C6F5) 4] exhibe un estado básico aislado de S = 9/2 hasta 300 K.
- Se observó una lenta relajación magnética en ausencia de un campo aplicado.
- Se determinó una barrera de inversión de espín efectiva de 87 cm-1, la más grande para un grupo de metales de transición.
- Se observaron histeresis magnética y bloqueo por debajo de 3,6 K.
Conclusiones:
- La superposición orbital directa entre metales contribuye al estado fundamental de alto espín estable.
- El acoplamiento de centros metálicos de baja coordenada mejora efectivamente la anisotropía magnética y ralentiza la relajación magnética.
- Este trabajo presenta una estrategia prometedora para el desarrollo de materiales magnéticos avanzados basados en grupos de metales de transición.
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