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Identificación del estado de oxidación +2 para el uranio en un complejo molecular cristalino, [K(2.2.2-cryptand)
Matthew R MacDonald1, Megan E Fieser, Jefferson E Bates
1Department of Chemistry, University of California , Irvine, California 92697-2025, United States.
Journal of the American Chemical Society
|August 30, 2013
Resumen
Los investigadores sintetizaron el primer complejo molecular aislable de uranio (((2+), [K ((2.2.2-cryptand) ][Cp'3U], a través de la reducción de flash. Se confirmó que este nuevo complejo de uranio es distinto del hidruro de uranio (((3+).
Área de la Ciencia:
- Química organometálica de las sustancias orgánicas.
- Química del uranio en su composición.
- La química de la coordinación es química de la coordinación.
Sus antecedentes:
- Los complejos de uranio se encuentran típicamente en estados de oxidación más altos.
- El aislamiento y la caracterización de las especies de uranio de baja valencia presenta desafíos significativos.
- Estudios anteriores no han informado de complejos estables, moleculares de uranio ((2+).
Objetivo del estudio:
- Para sintetizar y caracterizar el primer uranio molecular aislable ((2+) complejo.
- Para diferenciar el complejo sintetizado de uranio (((2+) de los potenciales subproductos de hidruro de uranio (((3+).
- Para dilucidar la estructura electrónica y el estado fundamental del nuevo complejo de uranio.
Principales métodos:
- Reducción instantánea de Cp'3U utilizando grafito de potasio y 2.2-criptand.
- Síntesis del complejo de hidruro de uranio (((3+) mediante adición de KH a Cp'3U y reducción de H2.
- Análisis cristalográfico para confirmar la identidad estructural.
- Cálculos de la teoría funcional de la densidad (DFT) para la determinación de la estructura electrónica.
Principales resultados:
- Aislamiento del cristalino [K(2.2.2-criptando]][Cp'3U], el primer complejo molecular U(2+).
- Confirmación de que el complejo U(2+) sintetizado es distinto del complejo U(3+) hidruro.
- Los cálculos de DFT predijeron un estado básico de quinteto de 5f(3) 6d(1) para el anión [Cp'3U](-).
- Las fuertes transiciones observadas en el espectro óptico coincidieron con las predicciones de DFT.
Conclusiones:
- Se ha logrado la síntesis y aislamiento exitosos de un complejo molecular U2+).
- La estructura electrónica del complejo U(2+) se caracteriza por un quinteto de estado básico de 5f(3) 6d(1).
- Este trabajo abre nuevas vías para explorar la química de las especies de uranio de baja valencia.
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