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化学学报
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化学学报 ›› 2007, Vol. 65 ›› Issue (22): 2510-2514. 上一篇    下一篇

研究论文

Li＋在基于N,N-二甲基甲酰胺混合溶剂中的溶剂化

轩小朋，王键吉*，赵培正，赵扬   

  1. (河南师范大学化学与环境科学学院 新乡 453007)
  • 投稿日期:2006-12-26 修回日期:2007-06-11 发布日期:2007-11-28
  • 通讯作者: 王键吉

Solvation of Lithium Ion in N,N-Dimethylformamide-based Mixtures

XUAN Xiao-Peng; WANG Jian-Ji*; ZHAO Pei-Zheng; ZHAO Yang   

  1. (School of Chemical and Environmental Sciences, Henan Normal University, Xinxiang 453007)
  • Received:2006-12-26 Revised:2007-06-11 Published:2007-11-28
  • Contact: WANG Jian-Ji

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利用红外和拉曼光谱技术研究了Li＋在不同浓度、不同溶剂组成的LiBF4/N,N-二甲基甲酰胺-乙腈、LiBF4/N,N-二甲基甲酰胺-四氢呋喃电解质溶液中的优先溶剂化现象. 红外和拉曼光谱的分析表明, Li＋主要与DMF分子相互作用, 导致该分子的C＝O伸缩振动谱带、N—C＝O形变谱带、CH3摇摆谱带等发生了分裂. Li＋与其它溶剂分子的相互作用较弱, 谱带的分裂现象并不明显. Li＋溶剂化数的计算显示, Li＋第一溶剂化层内DMF分子的数目一般大于2, 这说明 Li＋在混合溶剂体系内优先与DMF分子相互作用. 量子化学计算支持了这一结论.

关键词: 四氟硼酸锂, N,N-二甲基甲酰胺, 乙腈, 四氢呋喃, 振动光谱

Solutions of lithium tetrafluoroborate in N,N-dimethylformamide-acetonitrile and N,N-dimethyl-
formamide-tetrahydrofuran mixed solvents have been investigated by infrared and Raman spectroscopies. New bands, due to Li＋ solvation, were detected in the region of the C＝O strectching, O＝C—N deformation and CH3 rocking modes for N,N-dimethylformamide. The change in band for the co-solvents was weak. The number of N,N-dimethylformamide molecules in the first solvation shell of Li＋ was calculated and the preferential solvation of lithium ion by N,N-dimethylformamide indicated. This result has been supported by our ab initio calculations.

Key words: lithium tetrafluoroborate, N,N-dimethylformamide, acetonitrile, tetrahydrofuran, vibrational spectroscopy