DOI: 10.1016/j.cplett.2021.138809  (OpenAccess)

Stationary states of systems with intermolecular interactions dominated by electrostatics: Structure of trimethylammonium and tetramethylammonium chlorides and bromides in the gas phase, monomers and dimers

This work reports the theoretical study carried out with the M06-2x functional and the aug-cc-pVTZ basis set of four ammonium and two phosphonium salts, Me₃NH⁺Cl^–, Me₃NH⁺Br^–, Me₄N⁺Cl^–, Me₄N⁺Br^–, Me₄P⁺Cl^– and Me₄P⁺Br^–. The structure of the monomeric and dimeric complexes (between 1 and 5 conformations each) has been analyzed in what concern geometries, energies and NH+ stretching frequencies. The ammonium geometries were successfully compared with the X-ray structures found in the CSD.