Lithium ion solvation in room-temperature ionic liquids involving bis(trifluoromethanesulfonyl) imide anion studied by Raman spectroscopy and DFT calculations.
Lithium ion solvation in room-temperature ionic liquids involving bis(trifluoromethanesulfonyl) imide anion studied by Raman spectroscopy and DFT calculations.
复制标题
DOI：
10.1021/jp076869m
复制
发表时间：
2007-10
期刊：
影响因子：
--
通讯作者：
Y. Umebayashi;T. Mitsugi;Shuhei Fukuda;T. Fujimori;K. Fujii;R. Kanzaki;M. Takeuchi;S. Ishiguro
中科院分区：
文献类型：
--
作者：
Y. Umebayashi;T. Mitsugi;Shuhei Fukuda;T. Fujimori;K. Fujii;R. Kanzaki;M. Takeuchi;S. Ishiguro
用拉曼光谱和密度泛函理论计算研究了锂离子在室温离子液体1-乙基-3-甲基咪唑双(三氟甲磺酰基)亚胺(EMI(+)TFSI(-))和N-丁基-N-甲基吡咯烷亚胺(BMP(+0TFSI(-)中的溶剂化结构。在298K下，测量了含Li(+)TFSi(-)的EMI(+)TFSi(-)和BMP(+)TFSi(-)在0.144-0.589和0.076-0.633 moldm(-3)范围内的拉曼光谱。随着锂离子浓度的增加，体相中游离TFSi(-)的744 cm-1谱带减弱，分析表明这两个TFSi(-)离子与金属离子结合的强度减小。锂离子可能是通过两个双齿TFSi(-)离子的O原子四配位的。我们以前的工作已经证实，TFSI(-)离子涉及C(1)(顺)和C(2)(反)对称的两种构象处于平衡状态，并且C(1)构象的偶极矩明显大于C(2)构象的偶极矩。在此基础上，利用理论密度泛函理论计算了可能的溶剂化离子簇[Li(C(1)-TFSI(-))(2)](-)、[Li(C(1)-TFSI(-))(C(2)-TFSI(-))](-)和[Li(C(2)-TFSI(-))(2)](-)的几何构型和SCF能量。结果表明，在锂离子附近，C(1)构象比C(2)构象更具优势。
The solvation structure of the lithium ion in room-temperature ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMI(+)TFSI(-)) and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (BMP(+0TFSI(-)) has been studied by Raman spectroscopy and DFT calculations. Raman spectra of EMI(+)TFSI(-) and BMP(+)TFSI(-) containing Li(+)TFSI(-) over the range 0.144-0.589 and 0.076-0.633 mol dm(-3), respectively, were measured at 298 K. A strong 744 cm-1 band of the free TFSI(-) ion in the bulk weakens with increasing concentration of the lithium ion, and it revealed by analyzing the intensity decrease that the two TFSI(-) ions bind to the metal ion. The lithium ion may be four-coordinated through the O atoms of two bidentate TFSI(-) ions. It has been established in our previous work that the TFSI(-) ion involves two conformers of C(1) (cis) and C(2) (trans) symmetries in equilibrium, and the dipole moment of the C(1) conformer is significantly larger than that of the C(2) conformer. On the basis of these facts, the geometries and SCF energies of possible solvate ion clusters [Li(C(1)-TFSI(-))(2)](-), [Li(C(1)-TFSI(-))(C(2)-TFSI(-))](-), and [Li(C(2)-TFSI(-))(2)](-) were examined using the theoretical DFT calculations. It is concluded that the C(1) conformer is more preferred to the C(2) conformer in the vicinity of the lithium ion.