N,N′‐Bis(trifluoromethylsulfonyl)oxamidates: Synthesis and Thermal, Electrochemical, Spectroscopic, and Structural Properties

Abstract

AbstractSalts of the N,N′‐bis(trifluoromethylsulfonyl)oxamidate dianion (12–) were obtained by deprotonation of the oxamide {CF3SO2NHC(O)}2 (H21) with triethylamine, tri‐n‐octylamine, 1‐methylimidazole (MIM), and lithium hydride in yields of 61–92 %. The synthesis of H21 starting from oxalyl chloride and Na(NHSO2CF3) was improved. The salts Li21, [Et3NH]21, [nOct3NH]21, and [HMIM]21 were characterized by multinuclear NMR, IR, and Raman spectroscopy, mass spectrometry, and thermal and elemental analysis. The electrochemical stability of dianion 12– was studied by cyclic voltammetry on solutions of its lithium salt. The electrochemical properties are compared to those of H21. The conductivity of Li21 in DME was found to be lower than those of Li[BF4] and LiCF3SO3. The structures of 1∞[Li21·2THF], [Et3NH]21, [nOct3NH]21, and [HMIM]21 were studied by single‐crystal X‐ray diffraction. In the solid state, dianion 12– acts as a chelating ligand toward Li+ and forms bifurcated hydrogen bonds with the N–H moieties of the organic cations. The discussion of selected spectroscopic and structural properties is aided by DFT calculations.