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Complejos estables de niobio y tántalo monovalentes formalmente cerovalentes y diamagnéticos basados en los ligandos
P James Daff1, Michel Etienne, Bruno Donnadieu
1Laboratoire de Chimie de Coordination du CNRS, UPR 8241, 205 Route de Narbonne, 31077 Toulouse Cedex 4, France.
Journal of the American Chemical Society
|April 11, 2002
Resumen
Este estudio sintetiza complejos de niobio y tántalo con cerovalencia rara utilizando una nueva reacción. Estos complejos exhiben un diamagnetismo inesperado debido a la deslocalización de electrones en los ligandos, desafiando los modelos tradicionales de estructura electrónica.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Coordinación Química de la Coordinación
Sus antecedentes:
- La síntesis de complejos de metales de transición de baja valencia es crucial para comprender las estructuras electrónicas y la reactividad.
- Los complejos pseudooctaédricos de niobio y tántalo con configuraciones zerovalentes son raros y presentan propiedades electrónicas únicas.
Objetivo del estudio:
- Para sintetizar y caracterizar de manera eficiente nuevos complejos de niobio y tántalo pseudooctaédricos formalmente zerovalentes y monovalentes.
- Para investigar la estructura electrónica y las propiedades magnéticas de estos complejos inusuales.
Principales métodos:
- Síntesis de complejos de niobio y tántalo utilizando metal sódico y 1,4-diisopropil-1,4-diaza-1,3-dieno (iPr(2)-dad).
- Caracterización mediante cristalografía de rayos X y espectroscopia.
- Análisis computacional utilizando la Teoría Funcional de la Densidad (DFT).
Principales resultados:
- Síntesis eficiente de Nb ((iPr((2)-dad) (((3) (52% de rendimiento) y Ta ((iPr(2)-dad) ((3) (33% de rendimiento).
- Formación de complejos diamagnéticos monovalentes [M(iPr(2)-dad) ((3)][BPh ((4) ] tras la oxidación.
- Los cálculos de DFT revelaron una fuerte división orbital t(2g), lo que lleva al diamagnetismo y la localización de electrones en los ligandos.
Conclusiones:
- Los complejos formalmente zerovalentes se describen mejor como M(+) con ligandos aniónicos, M(iPr(2)-dad)(3) = M(+) iPr(2)-dad (-).
- Esta configuración electrónica, M(+) iPr(2)-dad (-), explica el diamagnetismo observado en estos complejos pseudooctaédricos de niobio y tántalo.
- Los hallazgos desafían los modelos de estructura electrónica convencionales para complejos de metales de transición de baja valencia.
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