Binding of Transition-Metal Ions to Curved π Surfaces: Corannulene and Coronene

Abstract

Calculations and comparisons were made for a set of seven metal cations binding to corannulene and coronene, namely, the three alkalis Li+, Na+, and K+ and the four transition-metal ions Ti+, Cr+, Ni+, and Cu+ (combined with literature results for Li+/corannulene). In the case of corannulene, the most favorable binding site for Ti+ and Ni+ is η6 over the six-membered ring on the convex face, whereas for Li+, Na+, K+, and Cr+, the five-membered η5 ring site on the convex face is about equally good. Cu+ slightly prefers binding at η2 edge sites rather than ring-centered sites on corannulene, but edge locations for several other ions were not found to be favored, in contrast to results reported for C60. For the alkalis, binding to the convex (outside) face is slightly favored relative to binding to the concave face, whereas for the transition metals, a much larger preference for outside binding is found, particularly for the η5 sites. An approximate point-charge model calculation is used to separate the elec...