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Estructuras y comportamiento dinámico de grandes jaulas de coordinación poliédricas: una inusual interconversión de
Andrew Stephenson1, Stephen P Argent, Thomas Riis-Johannessen
1Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom.
Journal of the American Chemical Society
|December 24, 2010
Resumen
Las nuevas jaulas de coordinación formadas por un ligando puente bis-bidentado (L) con metales de transición muestran nuevas estructuras. La jaula prismática trigonal de cadmio (Cd) es el producto termodinámico estable en solución, que se forma durante semanas a partir de una jaula más grande.
Área de la Ciencia:
- Coordinación Química de la Coordinación
- Química supramolecular de las moléculas.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- La síntesis de jaulas de coordinación poliédricas utilizando ligandos puentes es un área clave en la química supramolecular.
- El ligando L, {α,α-bis[3-(2-piridil) pirazol-1-il]-1,4-dimetilbenceno}, contiene dos unidades quelantes de pirazolil-piridina, lo que permite la formación de estructuras complejas.
- Estudios previos han demostrado la formación de jaulas cúbicas octanucleares con Ni (II).
Objetivo del estudio:
- Para explorar la reacción del ligando puente bis-bidentado L con varias dicciones de metales de transición (Cu ((II), Zn ((II), Cd ((II)).
- Caracterizar las jaulas de coordinación resultantes, centrándose en nuevos tipos estructurales.
- Para investigar la estabilidad de la solución y las vías de formación de estas jaulas de coordinación.
Principales métodos:
- Reacción de las dicciones de metales de transición (Cu ((II), Zn ((II), Cd ((II)) con el ligando L en una proporción de 2M: 3L.
- Caracterización estructural de las jaulas de coordinación resultantes utilizando cristalografía de rayos X. Caracterización estructural de las jaulas de coordinación resultantes utilizando cristalografía de rayos X.
- Análisis del comportamiento de la solución utilizando espectrometría de masas por electrospray (ES-MS) y espectroscopia de RMN de 1H.
Principales resultados:
- El complejo Ni (II) formó una jaula cúbica octonuclear, consistente con hallazgos anteriores.
- Se formaron nuevas jaulas prismáticas trigonales [Cu ((6) L ((9)) ] ((BF ((4)) ((12)) con Cu ((II).
- Se observaron jaulas hexadecanucleares sin precedentes [M(16) L((24)]X(32) con un núcleo de tetraedro truncado tetracapado sesgado para Zn(II) y Cd(II).
- El prisma trigonal hexanuclear [Cd(6) L(9) ]((BF(4)) ((12) fue identificado como el producto termodinámico de Cd(II) en solución, formado por el reordenamiento de la jaula [Cd(16) L(24) ] durante varias semanas.
Conclusiones:
- El ligando puente bis-bidentado L puede ensamblarse en diversas jaulas de coordinación poliédricas con diferentes metales de transición.
- La jaula prismática trigonal es el producto termodinámicamente favorecido para el Cd (II) en solución, a pesar de la formación inicial de una jaula hexadecanuclear más grande.
- Este estudio pone de relieve la naturaleza dinámica de la formación de la jaula de coordinación y el reordenamiento en solución.
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