First-Principles Calculations of Potassium Amidoborane KNH₂BH₃: Structure and ³⁹K NMR Spectroscopy

We have studied the structural, electronic, and vibrational properties of potassium amidoborane (KAB, KNH₂BH₃) using density-functional theory (DFT) calculations. The optimized structural parameters of KAB were found to be in good agreement with the experimental data. The electronic structure calculations suggested the covalent characters of N–H, B–H, and N–B as well as the ionic character of K. Moreover, we computed the ³⁹K NMR parameters of KAB and several K-containing materials by using the gauge-including projector augmented wave (GIPAW) approach, and found that the precise theoretical predictions and assignments of ³⁹K NMR parameters were possible. The DFT-GIPAW calculations were successfully applied to assign the ³⁹K MAS NMR signals of KAB to the crystallographically inequivalent K1 and K2 sites.