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Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants
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La espectroscopia de absorción de rayos X de borde K de azufre y la teoría funcional de la densidad dependiente del
Scott R Daly1, Jason M Keith, Enrique R Batista
1Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Journal of the American Chemical Society
|August 28, 2012
Resumen
Los ligandos del ácido dithiophosphinic con grupos de aryl orto-sustituidos muestran propiedades electrónicas únicas, aumentando la selectividad para la separación de actinide menor. Estos hallazgos guían el desarrollo avanzado del ciclo de combustible nuclear.
Área de la Ciencia:
- Coordinación Química de la Coordinación
- La radioquímica es la radioquímica.
- Química computacional es la química computacional.
Sus antecedentes:
- Los ácidos Dithiophosphinic exhiben una alta selectividad para separar los actinidos trivalentes menores (Am, Cm) de los lantánidos.
- La comprensión de los factores estructurales y electrónicos que rigen esta selectividad es crucial para el reprocesamiento de combustible nuclear.
Objetivo del estudio:
- Investigar las propiedades estructurales y electrónicas de los ligandos del ácido ditiofosfínico con diferentes sustituyentes de arilo.
- Para correlacionar estas propiedades con las elevadas selectividades de extracción observadas para actínidos menores.
Principales métodos:
- Síntesis y caracterización de una serie de complejos [PPh(4)][S(2)PR(2).
- Espectroscopia de absorción de rayos X (XAS) de borde K de azufre para sondear la estructura electrónica.
- Cálculos de la teoría funcional de densidad dependiente del tiempo (TDDFT) para modelar características espectrales y geometría molecular.
Principales resultados:
- Se observaron características espectrales distintas para el ligando sustituido por orto-trifluorometilfenilo (5), que se correlacionan con una alta selectividad.
- Los cálculos de TDDFT revelaron que los orto-sustitutos inducen efectos estéricos, causando la rotación del grupo arilo y la simetría molecular reducida.
- Este cambio estructural suaviza el ligando al elevar las energías orbitales de valencia de azufre y mejorar la mezcla orbital.
Conclusiones:
- Sulfur K-edge XAS y TDDFT revelan propiedades electrónicas únicas de los ligandos de ácido dithiophosphinic orto-sustituidos.
- Los efectos estéricos de los orto-sustitutos influyen significativamente en la estructura electrónica de los ligandos y su "suavidad".
- Estos hallazgos proporcionan una base para el diseño de extractores mejorados para aplicaciones avanzadas del ciclo del combustible nuclear.
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