Journal article
Structural Characterization of the 1-Butyl-3-methylimidazolium Chloride Ion Pair Using ab Initio Methods
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, Vol.110(6), pp.2269-2282
02/16/2006
Handle:
https://hdl.handle.net/2376/114944
PMID: 16466265
Abstract
Ab initio theoretical methods are used to investigate the gas-phase ion pairs of the ionic liquid 1-butyl-3-methylimidazolium chloride. Multiple stable conformers with the chloride anion positioned (in-plane) around the imidazolium ring or above the C2−H bond are determined. The relative energy ordering of the conformers is examined at the B3LYP, MP2, and CCSD(T) levels. Zero-point energies, BSSE, and basis set effects are examined. For accurate results, correlation (dispersion) effects must be included. The most stable conformers are essentially degenerate and have the chloride H-bonding to, or lying above, the C2−H bond. Other conformers are found to lie ∼30 and ∼60 kJ mol-1 higher in energy. Results are compared with those from recent simulations and experimental studies. The effect of the chloride anion on rotation of the butyl chain is investigated and found to lower some rotational barriers while enhancing others. The origin of the rotational barriers is determined. The number and type of hydrogen bonds formed between the imidazolium cation and chloride anion is found to vary significantly among conformers. No evidence of a possible intra Calkyl−H···π interaction is obtained; however, hints of a Cl···π interaction are found. The vibrational spectrum of each conformer is examined, and the origin of multiple (H-bonding) features in the vibrational spectrum of the ionic liquid explained.
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Details
- Title
- Structural Characterization of the 1-Butyl-3-methylimidazolium Chloride Ion Pair Using ab Initio Methods
- Creators
- Patricia A HuntIan R Gould
- Publication Details
- The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, Vol.110(6), pp.2269-2282
- Academic Unit
- Molecular Biosciences, School of
- Publisher
- American Chemical Society
- Identifiers
- 99900548023001842
- Language
- English
- Resource Type
- Journal article