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Complejos de renio (IV) altamente anisotrópicos: nuevos ejemplos de imanes mononucleares de una sola molécula
José Martínez-Lillo1, Teresa F Mastropietro, Elsa Lhotel
1Departament de Química Inorgànica/Instituto de Ciencia Molecular (ICMol), Universitat de València , C/Catedrático José Beltrán 2, 46980 Paterna (València), Spain.
Journal of the American Chemical Society
|August 21, 2013
Resumen
Los nuevos complejos de renio (IV), (NBu4) 2 [ReBr 4 ] ox y (NBu4) 2 [ReCl 4 ] ox), demuestran las propiedades de los imanes mononucleares de una sola molécula. Estos compuestos exhiben una lenta relajación de magnetización y centros magnéticos anisotrópicos, allanando el camino para materiales magnéticos avanzados.
Área de la Ciencia:
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Ciencia de los materiales Ciencia de los materiales.
- Magnetoquímica es la Magnetoquímica.
Sus antecedentes:
- Los complejos de Renio (IV) son de interés por sus propiedades magnéticas.
- Los imanes mononucleares de una sola molécula (SMM) ofrecen potencial para el almacenamiento de datos de alta densidad y la computación cuántica.
Objetivo del estudio:
- Para sintetizar y caracterizar el complejo de renio (IV) complejo (NBu4) 2 [ReBr4 (ox) ] (1).
- Para investigar las propiedades magnéticas de (NBu4) 2 [ReBr4 ((ox) ] (1) e isostructural (NBu4) 2 [ReCl4 ((ox) ] (2).
- Para determinar los parámetros del tensor de división de campo cero y comprender el origen de la anisotropía magnética.
Principales métodos:
- Difracción de rayos X para la determinación de la estructura cristalina.
- Temperatura variable dc y ac mediciones de susceptibilidad magnética.
- Experimentos de magnetización dependientes del campo.
- Espectroscopia de resonancia paramagnética (EPR) de electrones de alta frecuencia y campo.
- Métodos computacionales que incluyen el espacio activo completo y la teoría funcional de la densidad (DFT).
Principales resultados:
- La estructura cristalina de (NBu4) 2[ReBr4(ox) ] (1) reveló aniones discretos [ReBr4(ox) ](2-) y cationes de tetra-n-butilamonio voluminosos, con unas interacciones intermoleculares mínimas.
- Ambos complejos exhiben características de imanes mononucleares de una sola molécula, mostrando una lenta relajación de la magnetización a bajas temperaturas.
- Los estudios de EPR determinaron un signo negativo para el tensor de división de campo cero, lo que indica una magnitud significativa y la rombicidad (E / D) debido al acoplamiento de espín-órbita y la simetría molecular baja.
- Las mediciones de magnetización y los cálculos teóricos proporcionaron estimaciones para los valores D y E.
Conclusiones:
- Los complejos sintetizados de renio (IV) son nuevos ejemplos de imanes mononucleares de una sola molécula.
- La anisotropía magnética se origina en una combinación de un fuerte acoplamiento espín-órbita y baja simetría molecular en el centro del renio.
- Estos hallazgos contribuyen a la comprensión y diseño de nuevos materiales magnéticos con propiedades sintonizables.
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