Current Density Maps, Magnetizability, and Nuclear Magnetic Shielding Tensors for Anthracene, Phenanthrene, and Triphenylene

Abstract

Ab initio magnetically induced π-electron (first-order) current density maps and second-order magnetic properties, i.e., magnetizabilies, proton, and 13 C magnetic shielding tensors, calculated at coupled Hartree−Fock level of theory by means of the continuous transformation of origin of the current density method (CTOCD), are presented for a series of polycyclic aromatic hydrocarbons. The reliability of the current density maps is documented by the nice agreement between theoretical values for principal values of magnetizabilities and proton magnetic shieldings and corresponding experimental data presently available. For all three of the molecules, the π-electron current flows mainly on the external circuit of carbon atoms. Other intense circulations localized on a single ring take place over the central hexagon of anthracene and, on the contrary, on the external hexagons of phenanthrene and triphenylene. In light of the results obtained in the present work, e.g., taking advantage of high quality current density maps, important details of the ring current model for the molecules under study can be reexamined. Eventually, it is shown that the fundamental information which can be gained from knowledge of the principal components of the magnetic response tensors is easily accessible by means of the CTOCD computational method adopted here.