Local structure of Iridium organometallic catalysts covalently bonded to carbon nanotubes.

16th International Conference on X-ray Absorption Fine Structure

Blasco, J.^1 ; Cuartero, V.^2 ; Subías, G.^1 ; Jiménez, M.V.^3 ; Pérez-Torrente, J.J.^3 ; Oro, L.A.^3 ; Blanco, M.^4 ; Álvarez, P.^4 ; Blanco, C.^4 ; Menéndez, R.^4

Institute de Ciencia de Materiales de Aragón, Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, C/Pedro Cerbuna 12, Zaragoza

50009, Spain^1

ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France^2

Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea-ISQCH, Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, Zaragoza

50009, Spain^3

Instituto Nacional Del Carbón, CSIC, P.O. Box 73, Oviedo

33080, Spain^4

关键词: Coordination shells;    Covalently bonded;    Esterification reactions;    Hydrogen transfer;    Imidazolium salt;    N-heterocyclic carbenes;    Organometallic catalysts;    Organometallic compounds;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/712/1/012052/pdf
DOI  :  10.1088/1742-6596/712/1/012052

来源: IOP

【 摘 要 】

Hybrid catalysts based on Iridium N-heterocyclic carbenes anchored to carbon nanotubes (CNT) have been studied by XAFS spectroscopy. Oxidation of CNT yields a large amount of functional groups, mainly hydroxyl groups at the walls and carboxylic groups at the tips, defects and edges. Different kinds of esterification reactions were performed to functionalize oxidized CNT with imidazolium salts. Then, the resulting products were reacted with an Ir organometallic compound to form hybrid catalysts efficient in hydrogen transfer processes. XANES spectroscopy agree with the presence of Ir(I) in these catalysts and the EXAFS spectra detected differences in the local structure of Ir atoms between the initial Ir organometallic compound and the Ir complexes anchored to the CNT. Our results confirm that the halide atom, present in the Ir precursor, was replaced by oxygen from -OH groups at the CNT wall in the first coordination shell of Ir. The lability of this group accounts for the good recyclability and the good efficiency shown by these hybrid catalysts.