Properties of fluorosulfate-based ionic liquids and geometries of (FO2SOH)OSO2F− and (FO2SOH)2O2SOF−
作者:Takeshi Enomoto、Kazuhiko Matsumoto、Rika Hagiwara
DOI:10.1039/c1dt11014d
日期:——
A room temperature ionic liquid (IL) based on the fluorosulfate anion (SO3Fâ) has been synthesized by the reaction of 1-ethyl-3-methylimidazolium (EMIm+) chloride and fluorosulfuric acid (HOSO2F). The viscosity, ionic conductivity, and electrochemical window of EMImSO3F at 25 °C are 46.6 mPa s, 10.8 mS cmâ1, and 4.3 V, respectively. According to a solvatochromic measurement using ILs, there is a trend in the donor ability of fluoro- and oxofluoroanions, PF6â < BF4â < N(SO2CF3)2â < SO3CF3â < SO3Fâ < PO2F2â, which is explained by the atomic charges obtained from quantum mechanical calculations. The 1â:â2 and 1â:â3 stoichiometric reactions of EMImCl and HOSO2F give EMIm(FO2SOH)OSO2F and EMIm(FO2SOH)2O2SOF, respectively. Both the salts are liquid at room temperature without a HOSO2F dissociation pressure (< 1 Pa) and have low viscosity and high ionic conductivity (9.2 mPa s and 30.8 mS cmâ1 for EMIm(FO2SOH)OSO2F and 5.1 mPa s and 43.2 mS cmâ1 for EMIm(FO2SOH)2O2SOF). The vibrational modes and bonding properties of these anionic species are discussed with the aid of quantum mechanical calculations. The (FO2SOH)OSO2Fâ anion in EMIm(FO2SOH)OSO2F does not have an inversion centre, which stands in contrast to the one with an inversion centre (e.g. observed in solid Cs(FO2SOH)OSO2F). The (FO2SOH)2O2SOFâ anion in EMIm(FO2SOH)2O2SOF is characterized by vibrational spectroscopy under Cs symmetry.
通过 1-乙基-3-甲基咪唑(EMIm+)氯化物和氟硫酸(HOSO2F)的反应,合成了一种基于氟硫酸阴离子(SO3Fâ)的室温离子液体(IL)。在 25°C 时,EMImSO3F 的粘度、离子电导率和电化学窗口分别为 46.6 mPa s、10.8 mS cmâ1 和 4.3 V。根据使用 ILs 进行的溶解变色测量,氟离子和氧氟离子的供体能力呈 PF6â < BF4â < N(SO2CF3)2â < SO3CF3â < SO3Fâ < PO2F2â 的趋势,这可以用量子力学计算得到的原子电荷来解释。EMImCl 和 HOSO2F 的 1â:â2 和 1â:â3 化学计量反应分别生成 EMIm(FO2SOH)OSO2F 和 EMIm(FO2SOH)2O2SOF。这两种盐在室温下都是液态,没有 HOSO2F 的解离压力(< 1 Pa),具有低粘度和高离子电导率(EMIm(FO2SOH)OSO2F 为 9.2 mPa s 和 30.8 mS cmâ1 ,EMIm(FO2SOH)2O2SOF 为 5.1 mPa s 和 43.2 mS cmâ1 )。本文借助量子力学计算讨论了这些阴离子物种的振动模式和成键特性。EMIm(FO2SOH)OSO2F 中的 (FO2SOH)OSO2Fâ 阴离子没有反转中心,这与具有反转中心的阴离子(例如在固态 Cs(FO2SOH)OSO2F 中观察到的)形成了鲜明对比。EMIm(FO2SOH)2O2SOF 中的 (FO2SOH)2O2SOFâ 阴离子是在 Cs 对称条件下通过振动光谱来描述的。