Magnetism in hydro- and dehydrogenated benzene

Recently, it has been shown that selective hydrogenation of Polycyclic Aromatic Hydrocarbons (PAH) can lead to high spin molecules. In particular, this is the case of some forms of hydrogenated coronene and coranulenne. In this work, mono‐ and multi‐determinantal methods are used to show that hydrogenation of benzene, and dehydrogenation of benzene and coronene (a highly unlikely process), may lead to species whose ground states are characterized by a large spin degeneracy. Results for dehydrogenated coronene can be explained by Lieb's theorem for bipartite lattices. On the other hand, the theorem does not predict the correct spin of ground states for various forms of hydrogenated and dehydrogenated benzene (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)