Ionic liquids containing boron-centered cations supported by O-donor amide ligands: Synthesis, spectroscopy, thermochemistry and cyclic voltammetry

• Stable boronium ions can be formed using amides as ligands to the boron center • Select amide-boronium cations paired with the Tf 2 N - anion are ionic liquids • The thermal and electrochemical stability of the new ionic liquids are comparable to ILs with more familiar cations A key impetus for early studies on ionic liquids was the search for non-volatile electrolytes. While this faded from the forefront of IL research for many years, it has reemerged as a focus of keen interest. An important objective in the pursuit of suitable electrolytes is the control of properties such as electrochemical windows, ion diffusivity and so on. This, in turn, invites the study of ILs with ions of unusual structures or compositions. One recent subclass that has emerged are ILs based around boron-centered cations - boronium ions. Herein we describe a new group of boronium containing ILs in which the latter cations are supported by amide ligands. The new compounds have been thoroughly characterized by multinuclear NMR spectroscopy, DSC, TGA, and cyclic voltammetry. Single-crystal X-ray structures have also been obtained for a number of the cations when paired with the BPh 4 - anion.