1,3-Dimethoxy-2-methylimidazolium bis(trifluoromethanesulfonyl)imide

Abstract

, was obtained by the methylation of 1-hydroxy-2-methylimidazole 3-oxide and subsequent ion metathesis. In the crystal, C-HÁ Á ÁO S hydrogen bonds and OÁ Á Á interactions are observed. Structure descriptionThe molecular structure of the title compound is shown in Fig. 1. The ions which build this salt, both 1,3-dialkyloxyimidazolium cations (Laus et al., 2010) and the bis(triflimide) anion (Bentivoglio et al., 2009;Laus et al., 2011), are known to exist as syn/anti conformers in the solid state. Thus, the methoxy substituents of the cation adopt an anti conformation with a C5-O1Á Á ÁO2-C6 torsion angle of 170.6 (4) . The bis(triflimide) anion also assumes an anti conformation with a C7-S1Á Á ÁS2-C8 torsion angle of 174.9 (2) . Each cation donates three C-HÁ Á ÁO S hydrogen bonds to three anions (Fig. 2). The hydrogen-bond parameters are summarized in Table 1. An intriguing intermolecular interaction between atom O3 of the anion and the system of the imidazolium ring is observed. The pertinent O3Á Á ÁCg distance is 2.971 Å , where Cg is the centroid of the heterocyclic ring. This interaction is directional with an S1 O3Á Á ÁCg angle of 152 . The crystal packing is shown in Fig. 3.The cation in the structure of the related 1,3-dimethoxy-2-methylimidazolium tris(-pentafluoroethyl)trifluorophosphate displayed a syn geometry (Laus et al., 2007). AnionÁ Á Á interactions have been observed in related imidazolium salts (Froschauer et al., 2012). The O3Á Á Á interaction and C-HÁ Á ÁO S hydrogen bonds are shown as dashed lines (see Table 1). The centroid of the imidazole ring is drawn as red sphere. Table 1 Hydrogen-bond geometry (Å , ). Figure 3The crystal packing of the title compound viewed along the b axis showing the O3Á Á Á interactions. Figure 1The asymmetric unit of the title compound, showing the atom labels and 50% probability displacement ellipsoids for non-H atoms. of Synthesis and crystallizationA suspension of 1-hydroxy-2-methylimidazole-3-oxide (5.09 g, 44.6 mmol) and dimethyl sulfate (9.0 ml, 100 mmol) in H 2 O (5.0 ml) was stirred at room temperature for 30 min. Calcium carbonate (6.35 g, 63.4 mmol) and H 2 O (6.0 ml) were then added to the slurry, and a slight increase of temperature was observed. The mixture was stirred for 15 h. Then hydrochloric acid (36%; 11.0 ml, 129.2 mmol) was added in portions and stirred for 2 h, resulting in a clear solution. Lithium bis(trifluoromethanesulfonyl)imide (13.0 g, 44.9 mmol) was added, whereupon crystallization of the product occurred. After stirring for 1 h, the mixture was extracted with CH 2 Cl 2 (3 Â 50 ml). The combined organic phases were then washed with H 2 O (100 ml) and dried over Na 2 SO 4 . The solvent was removed under reduced pressure, and the product was dried at 75 C in vacuum (< 1 mbar). On cooling to room temperature the product was obtained as a colourless crystalline solid (yield 97%), mp. 66 C.

Crystal structure and Hirshfeld surface analysis of 2,4-diamino-6-phenyl-1,3,5-triazin-1-ium 4-methylbenzenesulfonate

“…3, Table 1). A similar interaction was observed in 1,3-dimethoxy-2-methylimidazolium bis(trifluoromethanesulfonyl)imide (Partl et al,2016). interactions are also observed between the anionic rings, with a centroid-tocentroid distance of 3.9192 (13) Å .…”