A theoretical ab initio study of [n.n]paracyclophane complexes with cations

Geometries and binding energies of complexes of Li+ and Na+ cations with benzene, several [n.n]paracyclophanes (n = 2,3) and a triple-layered [2.2]paracyclophane are computed and compared using ab initio calculations. We have recently demonstrated that the binding capability toward cations of [2.2]paracyclophane using one aromatic ring is superior to benzene in ∼10 kcal/mol. This unexpected difference is explained by the reduction, upon complexation, of the repulsive interaction of the π-systems. In the present work, we demonstrate that the binding ability of the next member of the cyclophane series [3.3]paracyclophane and the triple-layered [2.2]paracyclophane is even superior than [2.2]paracyclophane.