Study of the interaction between aniline and CH3CN, CH3Cl and CH3F

A computational study of dimers formed by aniline and one or two CH3X molecules, X being CN, Cl or F, was carried out to elucidate the main characteristics of the interacting systems. Two different structures were found for each of the dimers, depending on the relative location of the CH3X molecule with respect to the NH2 hydrogen atoms. The most stable complex is formed with acetonitrile, with a complexation energy amounting to -27.0 kJ/mol. Methyl chloride and methyl fluoride form complexes with complexation energies amounting to -18.1 and -17.5 kJ/mol, respectively, though the structural arrangement is quite different for both structures. In most complexes, the leading contribution to the stabilization of the complex is dispersion, though the electrostatic contribution is almost as important. Three different minima were obtained for clusters containing two CH3X molecules depending on the side they occupy with respect to the phenyl ring. The complexation energies for these structures amount to -58.5, -38.6 and -36.3 kJ/mol for acetonitrile, methyl chloride and methyl fluoride, respectively.