Kameda Yasuo, Sato Koichi, Hasebe Ryo, Amo Yuko, Usuki Takeshi, Umebayashi Yasuhiro, Ikeda Kazutaka, Otomo Toshiya
Department of Material and Biological Chemistry, Faculty of Science , Yamagata University , Yamagata , Yamagata 990-8560 , Japan.
Graduate School of Science and Technology , Niigata University , 8050 Ikarashi, 2-no-cho , Nishi-ku, Niigata City 950-2181 , Japan.
J Phys Chem B. 2019 Jun 13;123(23):4967-4975. doi: 10.1021/acs.jpcb.9b03477. Epub 2019 May 29.
Neutron diffraction measurements have been carried out on 10 mol % LiTFSA (TFSA: bis(trifluoromethylsulfonil)amide) solutions in methanol- d and 2-propanol- d to obtain information on the solvation structure of Li. The detailed coordination structure of solvent molecules within the first solvation shell of Li was determined through the least-squares fitting analysis of the difference function between normalized scattering cross sections observed for Li/Li isotopically substituted sample solutions. The nearest-neighbor Li···O distance and coordination number determined for the 10 mol % LiTFSA-methanol- d solution are r = 1.98 ± 0.02 Å and n = 3.8 ± 0.6, respectively. In the 2-propanol- d solution, it has been revealed that 2-propanol- d molecules within the first solvation shell of Li take at least two different coordination geometries with the intermolecular nearest-neighbor Li···O distance of r = 1.93 ± 0.04 Å. The Li···O coordination number, n = 3.3 ± 0.3, is determined. Ion-pair formation in the LiTFSA-methanol and LiTFSA-2-propanol solutions has been investigated by the attenuated total reflection infrared spectroscopic method. Mole fractions of free, Li-bound, and aggregated TFSA are derived from the peak deconvolution analysis of vibrational bands observed for TFSA.
已对甲醇 - d 和 2 - 丙醇 - d 中 10 摩尔%的 LiTFSA（TFSA：双（三氟甲基磺酰）酰胺）溶液进行了中子衍射测量，以获取有关 Li 溶剂化结构的信息。通过对 Li/Li 同位素取代样品溶液观察到的归一化散射截面之间的差异函数进行最小二乘拟合分析，确定了 Li 第一溶剂化壳层内溶剂分子的详细配位结构。对于 10 摩尔%的 LiTFSA - 甲醇 - d 溶液，确定的最近邻 Li···O 距离和配位数分别为 r = 1.98 ± 0.02 Å 和 n = 3.8 ± 0.6。在 2 - 丙醇 - d 溶液中，已揭示 Li 第一溶剂化壳层内的 2 - 丙醇 - d 分子至少采取两种不同的配位几何结构，分子间最近邻 Li···O 距离为 r = 1.93 ± 0.04 Å。确定了 Li···O 配位数 n = 3.3 ± 0.3。已通过衰减全反射红外光谱法研究了 LiTFSA - 甲醇和 LiTFSA - 2 - 丙醇溶液中的离子对形成。游离、与 Li 结合和聚集的 TFSA 的摩尔分数是通过对 TFSA 观察到的振动带进行峰去卷积分析得出的。
