Synthesis and characterization of rare and highly hydrolysis-resistant boronium (+3) cations

Boronium (+3) cations, L4B3+, are rare and scarcely studied. But, thanks to their rigid tetrahedral shape and high cationic charge they may be promising tectons for creating hybrid organic-inorganic solids, especially since a single cation can serve as a nucleating center around which three anions can be assembled. However, the few boronium (+3) cations which have been reported are generally water-sensitive, a factor which is a potential impediment to the former endeavor (as is the case with many perovskite photovoltaics). Herein we report the synthesis and characterization (X-ray, NMR, DSC, TGA, CV) of multiple boronium (+3) salts, all of which are highly water stable across the 1-14 pH range. And, as a preliminary investigation of the template-tecton hypothesis, the BETI- [bis(pentafluoroethanesulfonyl)imide] salt of a representative cation was prepared. Significantly, the crystals of the latter were determined by X-ray crystallography to feature continuous, fluorine-rich veins.