A gradient-corrected hybrid Hartree–Fock-density functional study of the dihydrogen-bonded phenol–borane-trimethylamine complex

The global minimum on B3LYP, mPW1PW91, PBE1PBE and HF/6-31++G(d,p) standard and counterpoise-corrected PESs of the phenol–boranetrimethylamine neutral dimer corresponds to an O–Hδ+⋯δ−H–B dihydrogen-bonded structure. The calculated anharmonic O–H vibrational frequency shifts upon this interaction suggest that considering the counterpoise-corrected PESs instead of the standard ones at all DFT levels of theory leads to a significantly improved agreement with the experimental data, although all DFT levels somewhat overestimate the experimentally measured (anharmonic) O–H vibrational frequency shifts. The harmonic shifts are, however, in fortuitous excellent agreement with the experiment. NBO and AIM analyses of the studied complex are carried out as well.