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El uso de la arquitectura molecular para controlar la reactividad de un triplet de vinilnitreno

Sujan K Sarkar¹, Onyinye Osisioma¹, William L Karney²

¹Department of Chemistry, University of Cincinnati , Cincinnati, Ohio 45221, United States.

Journal of the American Chemical Society

|October 25, 2016

Resumen

La fotólisis de luz visible del azido de vinilo genera vinilnitreno triplo, que se dimeriza para formar heterodímeros. Este método permite la formación selectiva de vinilnitrenos triplet para aplicaciones sintéticas, creando nuevos enlaces carbono-nitrógeno.

Área de la Ciencia:

Fotoquímica orgánica
Mecanismos de reacción
Espectroscopia

Sus antecedentes:

Los vinilnitrenos son productos intermedios reactivos.
Comprender su formación y reactividad es crucial para la química sintética.

Objetivo del estudio:

Para investigar la fotólisis de la 3-azido-1-indenona.
Caracterizar el intermediario del vinilnitreno transitorio.
Para explorar la utilidad sintética de los vinilnitrenos triplet.

Principales métodos:

Fotólisis mediante LED y lámpara de arco de mercurio.
Fotólisis con flash láser para la detección de transitorios.
Espectroscopia infrarroja (IR) y de resonancia de espín de electrones (ESR) en matrices criogénicas.
Teoría de la función de densidad (DFT) y cálculos CASSCF/CASPT2.

Principales resultados:

La fotólisis de la 3-azido-1-indenona produce el heterodimero 3 a través de la dimerización del vinilnitreno triple.
Se detectó y caracterizó espectroscópicamente el triplet de vinilnitreno (32).
Los datos de la RSE indican un carácter 1,3-birádico significativo en el vinilnitreno triplet.
Los cálculos de DFT apoyan el mecanismo propuesto y destacan los efectos estéricos que impiden el cruce entre sistemas.
La pequeña brecha de energía entre los singlet y los triplet (10 kcal/mol) no conduce a un cruce entre sistemas.

Conclusiones:

Los vinilnitrenos triplet se pueden generar selectivamente utilizando luz visible.
Estos intermedios se dimerizan eficientemente, formando nuevos enlaces C-N.
Este enfoque fotolítico ofrece ventajas sintéticas para crear nuevos compuestos orgánicos.

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