Reactivity And Mechanisms Of Hydridic Hydrogen Of B-H In Ammonia Borane Towards Acetic Acids: The Ammonia B-Monoacyloxy Boranes

Non-classical acid-base neutralization reactions of ammonia borane (NH3 center dot BH3, AB) with acetic acids are moderate, affected by strengths of acetic acid and its chloro derivatives, and concentrations and ratios of reactants. The experiment results indicate that only one hydridic hydrogen of B-H in AB is substituted and fortunately, four ammonia B-monoacyloxy boranes (NH3 center dot BH2OOCR, R = CHnCl3-n, n = 0-3) are prepared. Two single crystals of 2NH(3)BH(2)OOCCH(2)Cl center dot C12H24O6 and 2NH(3)BH(2)OOCCHCl(2)center dot C12H24O6 were obtained and analyzed first. Theoretical calculations demonstrated that these reactions are two-step elimination-addition process that takes advantage of the formation of dihydrogen bonds (DHBs) and hydrogen bonds (HBs), and aminoborane (NH2BH2, AoB) is identified as the key intermediate.