Chemical Shifts and Ring Currents in Condensed Ring Hydrocarbons

A complete analysis has been made for each of the high-resolution proton magnetic resonance spectra of naphthalene, anthracene, pyrene, perylene, triphenylene, and coronene at infinite dilution in CS2 or CCl4. A partial analysis has been made for phenanthrene. The analyses yield absolute values for the chemical shifts and spin coupling constants. A correlation has been made between the π-bond order of the particular (C–C) bond and the spin coupling constant. Theoretical values for the ``ring current shifts'' were obtained using London type molecular orbital calculations. The agreement between experimental and theoretical values is satisfactory in that the relative positions of the proton shifts are correctly predicted in all cases.