Structure of methyl 4-(trimethylammonium)benzoate iodide studied by X-ray diffraction, DFT calculations, NMR and FTIR spectra

The structure of methyl 4-(trimethylammonium)benzoate iodide, 4-(Me)3N+C6H4CO2MeI−, (1a) has been determined by X-ray diffraction, DFT calculations and characterized by FTIR and NMR spectroscopy. The crystals are triclinic, space group P 1 ¯ . The electrostatic distances N+⋯I− vary between 4.423(3) and 5.152(2) Å. The interpretation of 1H and 13C NMR spectra has been based on 2D experiments and calculated GIAO/B3LYP/6-311G(d,p) magnetic isotropic shielding constants. The FTIR spectrum of the solid compound is consistent with the X-ray results. The probable assignments of the anharmonic experimental solid state vibrational frequencies of the investigated ester (1a) based on the calculated harmonic frequencies are proposed.