Making C–C Bonds with Gold Catalysts: A Theoretical Study of the Influence of Gold Particle Size on the Dissociation of the C–X Bond in Aryl Halides

The adsorption and activation of iodo-, bromo-, and chlorobenzene over gold catalysts of different size, including an extended Au(111) surface; three-dimensional Au38 and Au13 nanoparticles; and planar Au7, Au6, and Au3 clusters has been systematically investigated by means of periodic density functional theory calculations. Several adsorption modes have been explored for each molecule, and the relative stability of such modes and the degree of C–X or C–C bond activation has been rationalized in terms of their molecular orbital distribution. Analysis of the electronic properties of the gold catalyst models allows the explanation of the influence of particle size on adsorption and activation energies in the subnanometer regime, while inclusion of dispersion interaction corrections becomes crucial for describing the reactivity of larger nanoparticles.