Theory Meets Experiment for Noncovalent Complexes: The Puzzling Case of Pnicogen Interactions

A gas-phase nitrogen–nitrogen noncovalent interaction has been unveiled in the nitroethane–trimethylamine complex in an environment free from solvent and matrix effects using rotational spectroscopy in supersonic expansion. Different quantum chemical models (NOCV/CD and NBO) agree in indicating that this interaction largely prevails over the C−H⋅⋅⋅O and C−H⋅⋅⋅N hydrogen bonds. Furthermore, a SAPT analysis shows that electrostatic and dispersion interactions play a comparable role in stabilizing the complex. The conformational landscape exploration and stationary points characterization have been performed using state-of-the-art quantum-chemical computations providing significant insights on structure determination.