Crystal structure of Na[N(SO2CF3)2] and coordination environment of alkali metal cation in the M[N(SO2CF3)2] (M+ = Li+, Na+, K+, and Cs+) structures

• The crystal structure of Na[N(SO2CF3)2] was determined.
• The layered structure of polar and nonpolar regions was observed.
• Coordination environments of M+ in M[N(SO2CF3)2] (M+ = Li+, Na+, K+, and Cs+) were compared to each other.

Crystal structure of Na[TFSA] (TFSA− = bis(trifluoromethylsulfonyl)amide anion (N(SO2CF3)2−)) has been determined by single-crystal X-ray diffraction. This compound crystallizes in a monoclinic cell (space group: P21/n) with Z = 8 and two ion pairs in the asymmetric unit. Both the crystallographically independent TFSA− anions adopt a cis configuration with the CS⋯SC torsion angle of −25.2(2)° and 25.1(2)°. The Na+ cations have contacts primarily with five neighboring O atoms (2.344(3)–2.415(3) Å for Na1⋯O and 2.337(3)–2.451(3) Å for Na2⋯O) and secondarily with one O atom and one N atom (2.843(3) for Na1⋯O, 2.929(3) for Na1⋯N, 2.806(3) for Na2⋯O and 2.907(3) for Na2⋯N). Comparison of the present structure with the previously reported M[TFSA] (M+ = Li+, K+, and Cs+) structures revealed that all of them have layered structures composed of the cationic and anionic layers. Coordination environment of M+ in the M[TFSA] structures is discussed based on bond valence sum calculations.

The crystal structure of Na[N(SO2CF3)2] has been determined by single-crystal X-ray diffraction. The layered structure observed is compared with the previously determined M[N(SO2CF3)2] (M+ = Li+, K+, and Cs+) structures.Figure optionsDownload as PowerPoint slide