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Localización del espín y la carga en los conductores de radicales neutros a base de fenalenilo
Robert C Haddon1, Arindam Sarkar, Sushanta K Pal
1Department of Chemistry, University of California, Riverside, California 92521-0403, USA. haddon@ucr.edu
Journal of the American Chemical Society
|September 19, 2008
Resumen
El análisis estructural de los radicales basados en fenalenilo revela estructuras electrónicas deslocalizadas, no pi-dimeros, que provocan cambios en la conductividad. Esto reinterpreta las propiedades electrónicas de estos conductores moleculares.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química del estado sólido.
- Electrónica orgánica y electrónica orgánica.
Sus antecedentes:
- Los radicales neutros basados en fenalenilo son componentes clave en los conductores moleculares.
- Comprender la localización del espín y la carga es crucial para sus propiedades electrónicas.
- Estudios previos sugirieron la formación de pi-dimeros en algunos radicales.
Objetivo del estudio:
- Para analizar experimentalmente el grado de giro y localización de carga en conductores moleculares de radicales neutrales basados en fenalenilo.
- Reevaluar la estructura electrónica de los radicales de fenalenilo previamente reportados.
- Investigar el mecanismo detrás de la conductividad mejorada durante las transiciones de fase magnética.
Principales métodos:
- Desarrollo de un análisis estructural basado en experimentos.
- Utilizando la relación entre el orden de los bonos y su longitud.
- Difracción de rayos X de cristal único del radical etílico (1) a temperaturas variables (90 K a temperatura ambiente) para observar cambios estructurales y de densidad de electrones a través de la transición de fase magnética (~140 K).
Principales resultados:
- La conductividad mejorada en los radicales diméricos de etilo (1) y butilo (3) en la transición de fase magnética se debe a una estructura electrónica compleja y altamente deslocalizada, no a la formación de dímeros pi.
- Los radicales monoméricos (4, 12, 13) exhiben una distribución asimétrica de la densidad de electrones.
- El radical 11 es el único radical monomérico que se encuentra para mantener la deslocalización completa; los radicales de cadena pi (7, 8, 14, 15) conservan estructuras deslocalizadas.
Conclusiones:
- El estudio reinterpreta la estructura electrónica de los radicales basados en fenalenilo, haciendo hincapié en la deslocalización sobre la formación localizada de pi-dimero.
- El análisis estructural experimental proporciona una visión crítica de los mecanismos de conductividad de los conductores moleculares.
- Los hallazgos requieren una revisión de las interpretaciones de la estructura electrónica para numerosos radicales de fenalenilo estudiados en la última década.
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