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

Abstract 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.