Experimentally Determined Hückel Coefficients of Aromatic Hydrocarbons

Three theories of hyperfine coupling constants of hydrocarbon radical ions are compared, and the assumptions underlying the theories are discussed. The McConnell and the Colpa—Bolton theories are used to compute experimentally determined Hückel-type coefficients Ci, and tabulations of these values are included. These coefficients should be useful in calculations of various molecular parameters which depend upon molecular orbital results, since they are believed to be more accurate than purely theoretical values. The parameters Q and K are also tabulated and may be used for comparisons between the electronic structures of various radical ions. The enhancement factor Q/QoAv is particularly useful in this respect.