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Espectroscopia vibratoria y estructuras de los complejos de Ni+(C2H2)(n) (n =1-4)
Richard S Walters1, E Dinesh Pillai, Paul V R Schleyer
1Department of Chemistry, University of Georgia, Athens, 30602-2556, USA.
Journal of the American Chemical Society
|December 1, 2005
Resumen
Se estudiaron complejos catiónicos de níquel con acetileno utilizando espectroscopia y teoría. Los investigadores descubrieron que múltiples moléculas de acetileno se unen al níquel, formando estructuras de baja simetría, con un número de coordinación de 4.
Área de la Ciencia:
- Química Física es la química física.
- Química computacional es la química computacional.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- Los complejos catiónicos de níquel son relevantes en la catálisis y la ciencia de los materiales.
- La comprensión de las interacciones metal-ligando es crucial para el diseño de nuevos procesos químicos.
Objetivo del estudio:
- Para investigar la estructura y la unión de los complejos de cationes de níquel-acetileno.
- Para determinar el número de coordinación y los modos de unión de los ligandos de acetileno.
- Explorar la influencia de los átomos de gases raros en la estabilidad y propiedades complejas.
Principales métodos:
- Producción de complejos de cationes de níquel-acetileno utilizando la vaporización láser pulsada en un haz molecular.
- Selección de tamaño y espectroscopia de fotodisociación láser infrarrojo en la región de estiramiento C-H.
- Cálculos de la teoría funcional de la densidad (DFT) para modelar estructuras complejas y espectros.
Principales resultados:
- Los patrones de fragmentación indicaron un número de coordinación de 4 para los complejos de níquel catión-acetileno.
- Los espectros infrarrojos y los cálculos de DFT revelaron la formación del complejo pi, desplazando los tramos C-H a frecuencias más bajas.
- Se descubrió que los estados excitados de baja altitud casi degeneran con el estado fundamental.
- La unión de los átomos de gas raro causó sólo pequeñas perturbaciones.
- El experimento y la teoría confirmaron estructuras de baja simetría debido a la distorsión de Jahn-Teller y / o efectos estéricos.
- El complejo de Ni (((+) (((C (((2) H ((2)) ((4) exhibió una estructura casi tetraédrica.
Conclusiones:
- Los cationes de níquel forman complejos pi estables con el acetileno, con un número máximo de coordinación de 4.
- La distorsión de Jahn-Teller y los efectos estéricos impulsan la formación de estructuras de baja simetría.
- Los átomos de gas raros tienen un impacto mínimo en la estructura compleja del núcleo y la espectroscopia.
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