Video Experimental Relacionado
Updated: Jul 6, 2026
14:44
Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR
Published on: December 16, 2013
Química estructural de los aracno-nonaboranos
Jonathan Bould1, Robert Greatrex, John D Kennedy
1School of Chemistry, University of Leeds, Leeds, UK LS2 9JT.
Journal of the American Chemical Society
|June 20, 2002
Resumen
Los estudios estructurales revelan que los grupos de hidruro de aracno-boro con la geometría de i-nonanborano son consistentemente isostruturales. Este hallazgo respalda las predicciones computacionales recientes para las estructuras de hidruro de boro y los cambios químicos de RMN.
Área de la Ciencia:
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Química del estado sólido.
- Química estructural de las estructuras.
Sus antecedentes:
- Los grupos de hidruro de boro exhiben diversas estructuras y reactividad.
- La geometría del aracno-i-nonanborano es un motivo estructural clave en la química del hidruro de boro.
- Comprender la disposición precisa de los átomos, especialmente el hidrógeno, es crucial para caracterizar estos cúmulos.
Objetivo del estudio:
- Para dilucidar las estructuras detalladas de varios aniones de hidruro de aracno-boro y sus aductos.
- Para investigar la consistencia estructural del marco de aracno-i-nonanborano.
- Para correlacionar datos estructurales experimentales con cálculos teóricos.
Principales métodos:
- Estudios de difracción de rayos X de un solo cristal utilizando fuentes convencionales de tubos y sincrotrones.
- Determinación estructural a baja temperatura para ubicar con precisión todos los átomos, incluido el hidrógeno.
- Comparación de datos experimentales con predicciones computacionales (por ejemplo, cambios químicos de RMN 11B).
Principales resultados:
- Estableció la naturaleza isostructural de los grupos básicos de boro-hidruro con la geometría de aracno-i-nonanborano.
- Identificó una disposición consistente de tres átomos de hidrógeno puente y dos endoterminales en la cara abierta de estos cúmulos.
- Confirmó la estructura propuesta para el anión [arachno-B{9) H{13) -4-NCMe} a través de nuevos datos de difracción.
- Los resultados experimentales se alinean con las predicciones computacionales para las estructuras y los cambios de RMN.
Conclusiones:
- El marco aracno-i-nonanborano exhibe un motivo estructural conservado a través de varios derivados.
- La caracterización estructural proporciona un fuerte apoyo a los modelos teóricos de los grupos de hidruro de boro.
- Este trabajo refina nuestra comprensión de la colocación del átomo de hidrógeno en estos complejos aniones inorgánicos.
Videos de Conceptos Relacionados
02:34Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
01:46Oxidative Cleavage of Alkenes: Ozonolysis
In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
01:28Structures of Carboxylic Acid Derivatives
Structure of Carboxylic Acid Derivatives
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
01:19Structure of Amines
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...
01:04Structures of Aldehydes and Ketones
Vanillin—a flavoring agent in vanilla, cinnamaldehyde—a molecule responsible for the distinct smell of cinnamon, and acetone—a strong-smelling ingredient in nail polish removers, all belong to a class of carbonyl compounds called aldehydes and ketones (Figure 1). Although both aldehydes and ketones contain the characteristic carbonyl (C=O) bond, their chemical structures vary with respect to the groups directly attached to the carbonyl carbon.
In aldehydes (Figures 1a and 1b), the carbonyl...
In aldehydes (Figures 1a and 1b), the carbonyl...
01:15NMR Spectroscopy and Mass Spectrometry of Aldehydes and Ketones
In aldehydes, the hydrogen atom connected to the carbonyl carbon helps distinguish aldehydes from other carbonyl compounds using ¹H NMR spectroscopy. The closeness of aldehydic hydrogen to the electrophilic carbonyl carbon highly deshields the hydrogen atom causing its signal to appear around 10 ppm in the ¹H NMR spectra. α hydrogens split the aldehydic proton signal, which helps identify the number of α hydrogens in the molecule. For instance, one α hydrogen creates a doublet for an aldehydic...