The acidity/basicity of metal-containing ionic liquids: insights from surface analysis and the Fukui function

Abstract

Metal-containing ionic liquids (ILs) have been recognized as potential solvents, catalysts, catalyst precursors and reagents for many organic processes. In this work, several quantum-chemical parameters, including the surface electrostatic potential (Vs,max and Vs,min), the lowest surface average local ionization energy (I̅s,min), and the electrostatic potential at the position of an atom (EPnuc), were adopted to understand the acidity/basicity of metal-containing ILs. Chlorometallate-based ILs show stronger acidity than conventional ILs, because of the increased electron-deficiency of the imidazole ring upon the incorporation of metal chloride. For the ILs with the Ag-coordinated cations, the acidity tends to attenuate while the basicity becomes stronger, as compared to traditional ILs. In addition, the regional Fukui function was also used to assess the molecular distribution of the Lewis acidity/basicity of the ILs under study. Overall, the introduction of metals into either the cations or the anions influences the acidity/basicity of ILs to a large degree, which would be beneficial for their certain applications, such as catalysis and extraction. We hope that the results presented here will assist in the development of novel metal-containing ILs with desirable properties.

Lewis Acidity and Basicity of Mixed Chlorometallate Ionic Liquids: Investigations from Surface Analysis and Fukui Function

“…The acidity and basicity of these ILs were correlated with theoretically parameters [ 47 ]. Similar works have also been done by Wu and co-workers [ 48 ].…”

Halogen bonding interactions in ion pairs versus conventional charge-assisted and neutral halogen bonds: a theoretical study based on imidazolium species

“…M06-2x, developed by Zhao and Truhlar, has proved to be reliable in the description of various types of noncovalent interactions, [50][51][52] while the hybrid B3LYP functional has been widely utilized in the studies of cation-anion interactions in ILs. 34,39,[53][54][55][56] The basis set of Peterson and co-workers, aug-cc-pVDZ-PP, 57 obtained from the EMSL Basis Set Exchange, was used for the I atom. The (-PP) notation indicates that relativistic effective core potentials were employed for the core electrons, that is, 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 for I.…”

Identifying Different Halogen‐/Hydrogen‐Bonding Interaction Modes in Binary Systems that Contain an Acetate Ionic Liquid and Various Halobenzenes

“…The geometries of all monomer and complexes were fully optimized by using DFT theory at the B3LYP and M06‐2X levels by using the Gaussian 09 program . M06‐2X has been proved to be reliable in the characterizations of various noncovalent interactions, whereas the hybrid B3LYP functional has been widely applied in the study of cation–anion interactions in ILs . The basis set aug‐cc‐pVDZ‐PP was used for bromine and iodine atoms, taking relativistic effects into consideration.…”