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rdf:type
lifeskim:mentions
pubmed:issue
34
pubmed:dateCreated
2006-7-20
pubmed:abstractText
The intermolecular interaction energies of nine ion pairs of room temperature ionic liquids were studied by MP2/6-311G level ab initio calculations. The magnitude of the interaction energies of 1-ethyl-3-methylimidazolium (emim) complexes follows the trend CF(3)CO(2)(-) > BF(4)(-) > CF(3)SO(3)(-) > (CF(3)SO(2))(2)N(-) approximately PF(6)(-) (-89.8, -85.2, -82.6, -78.8, and -78.4 kcal/mol, respectively). The interaction energies of BF(4)(-) complexes with emim, ethylpyridinium (epy), N-ethyl-N,N,N-trimethylammonium ((C(2)H(5))(CH(3))(3)N), and N-ethyl-N-methylpyrrolidinium (empro) are not very different (-85.2, -82.8, -84.6, and -84.4 kcal/mol, respectively), while the size of the orientation dependence of the interaction energies follows the trend emim > epy approximately (C(2)H(5))(CH(3))(3)N > empro. Comparison with the experimental ionic conductivities shows that the magnitude and directionality of the interaction energy of the ion pairs play a crucial role in determining the ionic dissociation/association dynamics in the ionic liquids. The electrostatic interaction is the major source of attraction between ions. The induction contribution is small but not negligible. The hydrogen bonding with the C(2)-H of imidazolium is not essential for the attraction in the ion pair. The interaction energy of the BF(4)(-) complex with 1-ethyl-2,3-dimethylimidazolium (em2im) (-81.8 kcal/mol) is only 4% smaller than that of the emim complex.
pubmed:language
eng
pubmed:journal
pubmed:status
PubMed-not-MEDLINE
pubmed:month
Sep
pubmed:issn
1520-6106
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
109
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
16474-81
pubmed:year
2005
pubmed:articleTitle
Magnitude and directionality of interaction in ion pairs of ionic liquids: relationship with ionic conductivity.
pubmed:affiliation
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan. s.tsuzuki@aist.go.jp
pubmed:publicationType
Journal Article