Hydrogen-bonding interactions between [BMIM][BF4] and acetonitrile.
In this work, the interactions between a representative imidazolium-based ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and acetonitrile (CH3CN) were investigated in detail using attenuated total reflection infrared spectroscopy (ATR-IR), hydrogen nuclear magnetic resonance ((1)H NMR), and density functional theory calculations. The main conclusions are: (1) a number of species in the [BMIM][BF4]-CH3CN mixtures were identified with the help of excess infrared spectroscopy and quantum chemical calculations. The dilution process of the ionic liquid by acetonitrile was found to be the transformation from ion clusters to ion pairs. (2) The solvent molecules cannot break apart the strong Coulombic interaction between [BMIM](+) and [BF4](-) but can break apart the ion cluster into an ion pair within the concentration range investigated. The strength of hydrogen bonds between the C-Hs of [BMIM](+) and the N of acetonitrile is enhanced during the dilution process. (3) The methyl group of CH3CN locates above/below the imidazolium ring in the solution. These in-depth studies on the properties of the ionic liquid-acetonitrile mixed solvents may shed light on exploring their applications as reaction media in electrochemistry and chemical synthesis.
Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China. yuzhw@tsinghua.edu.cn.
Yan-Zhen
YZ
Zheng
Nan-Nan
NN
Wang
Jun-Jie
JJ
Luo
Yu
Y
Zhou
Zhi-Wu
ZW
Yu
D000097:Acetonitriles / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared
C419324:1-butyl-3-methylimidazolium tetrafluoroborate; D000097:Acetonitriles; D007093:Imidazoles; D052578:Ionic Liquids; D006859:Hydrogen; C032159:acetonitrile