Another look at organic/metal (O/M) interfaces: correlation with experiment

Abstract

Topological features of the electron density (ρ) at a bond critical point (BCP), determined by the quantum theory of atoms in molecules (QTAIM), were previously established as a determinative factor underlying the nature of an O/M-bonded interaction (P. M. Mitrasinovic, Can. J. Chem., 81:542–554, 2003). Herein, a general methodology for the extrapolation of the nature of the interfacial interactions is proposed by investigating the changes of organic/metal BCP parameters as consequences of both increasing the size and changing the shape of the metal surfaces. In particular, the adsorption of acrylonitrile (AN) on the model copper (Cu) clusters (Cu n , n = 9–14, 16, 18, 20) simulating the actual Cu(100) surface is analyzed. The electron density and its Laplacian ( ∇ 2) at the AN/Cu n BCPs are statistically correlated with experimental quantities, such as electron affinities (EAs) and ionization potentials (IPs) of metal surfaces. The dipole moment (DM), a chemical descriptor arising directly from the electron density distribution in both the overall (AN/Cu n ) model systems and the Cu n clusters, is found to be better-correlated with the experimentally determined EAs of the Cu n clusters than with calculated ones.