Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts
L M Martínez-Prieto1, I Cano1, A Márquez2
1LPCNO , Laboratoire de Physique et Chimie des Nano-Objets , UMR5215 INSA-CNRS-UPS , Institut des Sciences Appliquées , 135, Avenue de Rangueil , F-31077 Toulouse , France . Email: vanleeuw@insa-toulouse.fr ;
Chemical Science
|April 29, 2017
Summary
We developed novel platinum nanoparticles (Pt NPs) using imidazolium-amidinate ligands. These ligands strongly bind to Pt, enabling catalysis for ketone hydrogenation with tunable activity based on ligand substituents.
Area of Science:
- Nanomaterials Science
- Catalysis
- Surface Chemistry
Background:
- Ligand control is crucial for stabilizing metal nanoparticles (MNPs) and tuning their catalytic activity.
- Imidazolium-amidinate ligands offer strong binding to metal surfaces, influencing nanoparticle properties.
Purpose of the Study:
- To report the first instance of platinum nanoparticles (Pt NPs) ligated by imidazolium-amidinate ligands.
- To investigate the binding modes, stability, and catalytic performance of these functionalized Pt NPs.
Main Methods:
- Synthesis of Pt NPs ligated by imidazolium-amidinate ligands.
- Characterization using 15N NMR spectroscopy, XPS, IR, and 13C MAS NMR.
- Density Functional Theory (DFT) calculations for binding energy analysis.
- Evaluation of catalytic activity in ketone hydrogenation.
Main Results:
- Strong binding of amidinate anion to Pt surface atoms in both monodentate and bidentate coordination modes.
- DFT calculations confirmed high binding energies, indicating ligand stability.
- Spectroscopic evidence confirmed CO adsorption on Pt NPs, signifying available catalytic sites.
- Observed particle size-dependent Knight shift in 13C MAS NMR, experimentally verifying theoretical predictions for MNPs.
- Pt NPs demonstrated catalytic activity in ketone hydrogenation, with activity modulated by ligand substituents.
Conclusions:
- Imidazolium-amidinate ligands effectively stabilize Pt NPs and offer control over catalytic properties.
- The electronic nature of ligand substituents significantly impacts catalytic activity, particularly for electron-poor carbonyl groups.
- This study provides experimental validation for MNP theory and introduces a promising ligand system for catalysis.
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