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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Estabilidades de los carbenos: medidas independientes para singlets y triplets
Scott Gronert1, James R Keeffe, Rory A More O'Ferrall
1Department of Chemistry, Virginia Commonwealth University, 1001 W. Main Street, Richmond, Virginia 23284, United States. sgronert@vcu.edu
Journal of the American Chemical Society
|February 24, 2011
Resumen
Este estudio cuantifica las estabilidades termodinámicas de los carbenos utilizando entalpias de hidrogenación, revelando correlaciones entre las brechas singlet-triplet y las escalas de estabilidad para varios tipos de carbenos.
Área de la Ciencia:
- Química computacional es la química computacional.
- Química cuántica es la química cuántica.
- Química orgánica es la química orgánica.
Sus antecedentes:
- Los carbenos son reactivos intermedios cruciales en la síntesis orgánica.
- Comprender su estabilidad termodinámica es clave para predecir la reactividad.
- Es posible que las escalas de estabilidad existentes no capturen completamente las diversas estructuras de carbenos.
Objetivo del estudio:
- Para evaluar las estabilidades termodinámicas de 92 carbenos diversos (singlets y triplets).
- Desarrollar nuevas escalas de entalpía de estabilización de carbenos (CSE) para solteros y trillizos.
- Para investigar las relaciones estructura-estabilidad y estimar la aromaticidad en los carbenos cíclicos.
Principales métodos:
- Las entalpias de hidrogenación se calcularon utilizando el nivel teórico G3MP2.
- Análisis de las correlaciones entre las brechas singlet-triplet y las entalpias de hidrogenación.
- Desarrollo de escalas CSE separadas para carbenos singlet y triplet.
Principales resultados:
- Se observó una buena correlación entre las brechas singlet-triplet y las entalpías de hidrogenación singlet, con valores atípicos notables.
- Se establecieron nuevas escalas CSE, destacando las influencias estructurales en la estabilidad del carbeno.
- Se estimó que el imidazol-2-ilideno posee una energía de estabilización aromática de aproximadamente 20 kcal/mol.
Conclusiones:
- Las entalpias de hidrogenación proporcionan un método confiable para evaluar la estabilidad termodinámica de los carbenos.
- Las escalas CSE desarrolladas ofrecen información sobre la estabilidad de los carbenos singlet y triplet.
- El estudio demuestra la utilidad de los métodos computacionales para evaluar las propiedades de los carbenos, incluida la aromaticidad.
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