A theoretical study on the interaction of [Al(H2O)6]3+ and [Mg(H2O)6]2+ cations with fullerene (C60), coronene and benzene π-systems

Density functional theory (DFT), Bader's theory of atoms in molecules (AIM) and natural bond orbital (NBO) calculations have been used to understand the nature of the interaction between M(H2O)(6)(n+) (M = Mg2+, Al3+) complexes and fullerene, coronene and benzene pi-systems. The interaction energies were calculated for all the compounds and corrected for the basis set superposition error (BSSE). The results showed that the above pi-systems have larger interaction energies with Al(H2O)(6)(3+) than Mg(H2O)(6)(2+). Also the AIM topological parameters for the bond critical points (BCPs) between the M(H2O)(6)(n+) cations and the fullerene, coronene and benzene pi-systems confirmed that {[Al(H2O)(6)](3+)...fullerene) has a much stronger bonding interaction than the other systems. The calculated interaction energies correlate well with both the Wiberg bond indices and the global value of charge transfers from pi-systems to cations evaluated through natural population analysis. The calculations suggest that the ionic potential of the central metal ion in the M(H2O)(6)(n+) cation and the nature of pi-system are two influential factors that affect the strength and the nature of the interaction. (C) 2011 Elsevier Ltd. All rights reserved.