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EPR, ENDOR y estudios de estructura electrónica de la distorsión de Jahn-Teller en un nitruro de Fe (V)

George E Cutsail¹, Benjamin W Stein, Deepak Subedi

¹Department of Chemistry Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.

Journal of the American Chemical Society

|August 20, 2014

Resumen

Un nuevo complejo de nitruro de hierro de baja coordinación, un modelo para estados de alta oxidación, exhibe la distorsión de Jahn-Teller. Los cálculos de la estructura electrónica y las mediciones de ENDOR revelan información sobre su enlace y reactividad, particularmente para la transferencia de protones.

Área de la Ciencia:

Química Inorgánica La Química Inorgánica es la química inorgánica.
Química computacional es la química computacional.
La espectroscopia es una técnica de espectroscopia.

Sus antecedentes:

Los complejos de hierro de alto estado de oxidación de baja coordinación son modelos cruciales para los sistemas biológicos e industriales.
El complejo de nitruro de hierro sintetizado, [PhB((t) BuIm) 3Fe(V) N](+), presenta una configuración electrónica d.
Este complejo es susceptible a la distorsión de Jahn-Teller (JT) debido a su estado básico degenerado.

Objetivo del estudio:

Para analizar la estructura electrónica del complejo de nitruro de Fe (V) de baja coordinación.
Para investigar la interacción entre los tratamientos formales pseudo Jahn-Teller (PJT) y los cálculos químicos cuánticos.
Para entender las implicaciones de la distorsión JT en la reactividad del complejo.

Principales métodos:

Tratamiento extendido formal pseudo Jahn-Teller (PJT) de dos órbitas que incorpora mezcla de órbitas.
Nuevos métodos computacionales DFT/CASSCF para la determinación de la estructura electrónica.
Espectroscopia ENDOR pulsada de 35 GHz para obtener tensores hiperfinos y cuádrupolos para los ligandos de nitruro y boro.

Principales resultados:

El estudio revela una distorsión cuadrática de JT y una mezcla significativa de e-e en el complejo de nitruro de Fe (V).
El análisis de ENDOR indica un trianión de nitruro esférico con densidad de espín negativa y una anisotropía de carga mínima.
El análisis computacional de las órbitas fronterizas muestra que el descenso de simetría inducido por JT facilita la transferencia de protones o átomos H.

Conclusiones:

Un enfoque sinérgico que combina tratamientos formales y métodos computacionales avanzados proporciona una comprensión más profunda de la estructura electrónica del complejo.
El complejo de nitruro de Fe ((V) sirve como un modelo valioso para estados de alta oxidación, con implicaciones para la catálisis.
El efecto JT juega un papel crítico en la determinación de la reactividad de este nitruro de hierro de baja coordinación.

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