The influence of water molecule coordination onto the water-aromatic interaction. Strong interactions of water coordinating to a metal ion

Abstract

The interactions between water molecules (non-coordinating and coordinating) and aromatic rings were studied by analyzing data in the Cambridge Structural Database and by quantum chemical calculations. The results show the influence of water coordination to a metal ion; interactions of coordinating water are stronger. The MP2/def2-QZVP interaction energies of non-coordinating water and neutral aqua complexes [ScCl3(H2O)(3)], [ZnCl2(H2O)(4)], [CdCl2(H2O)(4)], and [ZnCl2(H2O)(2)] with benzene molecule are -3.36, -5.10, -5.43, -6.86, and -5.14 kcal mol(-1), respectively. Interactions of charged aqua complexes [ZnCl(H2O)(5)](+) and [Zn(H2O)(6)](2+) are stronger, -9.69 and -13.96 kcal mol(-1), respectively. The calculations also reveal strong long-range interactions: at the distance of 3.0 angstrom the interaction energies of neutral complexes are in the range of -4.11 to -4.91 kcal mol(-1), while interaction energies of charged complexes are -6.37 and -10.76 kcal mol(-1).