Reduction of Triple Bond in [B12H11NCR]− Anions by Lithium Aluminum Hydride: A Novel Approach to the Synthesis of N-Monoalkylammonio-Substituted closo-Dodecaborates

By reacting nitrilium derivative of the closo-dodecaborate anion, Bu4N[B12H11N≡CR] (where R = Me, Et, nPr, iPr, p-tolyl), with lithium aluminum hydride (LiAlH4), N-alkylammonium derivatives of the closo-dodecaborate anion, and Bu4N[B12H11NH2CH2R], were obtained. The reduction reaction procedure was optimized, achieving yields close to quantitative (90–95%). The structure of the compound Bu4N[B12H11NH2CH2CH3] was determined using X-ray structural analysis. It was found that substituting lithium aluminum hydride (LiAlH4) with sodium borohydride (NaBH4) leads to the same products but only upon heating, while the reaction with LiAlH4 proceeds at room temperature.