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Published on: March 24, 2018
Ionic liquids from cationic palladium(II) chelate complexes: preparation, thermal properties, and crystal structures
Hitoshi Hosokawa1, Yusuke Funasako, Tomoyuki Mochida
1Department of Chemistry, Graduate School of Science, Kobe University, Rokkodai, Nada, Hyogo 657-8501, Japan. tmochida@platinum.kobe-u.ac.jp.
New palladium(II) ionic liquids were synthesized using chelating ligands and bis(trifluoromethanesulfonyl)amide anions. These metal-containing ionic liquids exhibit distinct thermal behaviors, with some crystallizing and others forming glasses upon cooling.
Area of Science:
- Coordination Chemistry
- Materials Science
- Ionic Liquids
Background:
- Ionic liquids (ILs) are salts that are liquid below 100 °C.
- Metal-containing ILs offer unique properties for catalysis and materials applications.
- Palladium complexes are widely used in catalysis.
Purpose of the Study:
- To synthesize and characterize novel palladium(II) ionic liquids.
- To investigate the thermal properties and structural characteristics of these new compounds.
- To explore the influence of ligand structure on the behavior of palladium-based ILs.
Main Methods:
- Synthesis of palladium(II) chelate complexes with bis(trifluoromethanesulfonyl)amide anion.
- Differential Scanning Calorimetry (DSC) for thermal analysis (melting point, glass transition).
- X-ray crystallography for solid-state structure determination.
Main Results:
- Three palladium(II) ionic liquids, [Pd(acac)(Me4en)]Tf2N (1), [Pd(acac)(BuMe3en)]Tf2N (2), and [Pd(C8-acac)(Me4en)]Tf2N (3), were successfully prepared.
- Complex 1 crystallized upon cooling, while complexes 2 and 3 exhibited glass transitions around -40 °C.
- X-ray analysis revealed dimer-like arrangements of cations in complexes 1 and 3, with no direct cation-anion contacts in the solid state.
Conclusions:
- The synthesized palladium(II) ionic liquids display varied thermal properties, influenced by ligand structure.
- The structural analysis provides insights into the solid-state packing and interactions within these metal-containing ionic liquids.
- These findings contribute to the understanding and design of novel functional ionic liquids.
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