An insight into coordination ability of dicyanoimidazolato anions toward lithium in presence of acetonitrile. Crystal structures of novel lithium battery electrolyte salts

New generation of imidazole-derived salts was characterized by single-crystal X-ray diffraction experiments for the first time. Herein, we present crystal structures of lithium salts containing original 4,5-dicyanoimidazolato anions substituted with trifluoromethyl, pentafluoroethyl and heptafluoropropyl groups. Studied compounds crystallize as acetonitrile-solvated dimers with four-coordinate lithium cations. Structures of crystalline materials were examined with regard to the fine properties of electrolyte providing valuable information about coordination ability of substituted 4,5-dicyanoimidazolato anions. Anions act as ditopic N donor ligands containing additional weak fluorine donor-centers. Donor nitrogen atoms of imidazole and cyano groups, show slightly lower basicity than electroneutral acetonitrile solvent molecules coordinated to lithium. Presence of bulky substituents does not alter crystal structure and close-packed arrangement is observed.

Graphical abstractNovel generation of imidazole-derived salts was characterized by single-crystal X-ray diffraction experiments. Comprehensive crystal structure analysis provides valuable information about properties and coordination ability of substituted 4,5-dicyanoimidazolato anions.Figure optionsDownload full-size imageDownload as PowerPoint slide