Synthesis, spectroscopy, computational evaluation and first X-ray structural characterization of a primary amine containing boronium ion

Stable (CF3SO2)2N−, I− and BPh4- salts of the boronium ion [(tert-butylamine)(1-methylimidazole)BH2]+ have been isolated and characterized. A single-crystal X-ray structure of the BPh4- salt provides the first unambiguous proof for a boronium ion supported by a primary amine ligand.

Reaction of tert-butylamine · borane with I2 and 1-methylimidazole gives the iodide salt of a boronium ion incorporating a primary amine, believed to be the first such boronium characterized by X-ray crystallography. The cation is stable despite the presence of adjacent –BH2 and –NH2 units. The iodide is readily replaced by BPh4- and Tf2N− via metathesis in water. The latter salt is a room-temperature ionic liquid, the first boronium IL incorporating a primary amine.Figure optionsDownload as PowerPoint slide