A retrospective appraisal of the Pople point‐dipole model of ‘‘ring‐current’’ effects on 1H‐NMR chemical shifts in planar, condensed, benzenoid hydrocarbons

A set of well‐established, 1H‐NMR chemical shift data for 66 nonhindered protons in 16 different condensed, benzenoid hydrocarbons is systematically compared with predictions of (a) the Pople point‐dipole ’’ring‐current’’ model and (b) nine other distinct ring‐current approaches, of varying degrees of sophistication. Provided that it is based on relative ring‐current intensities calculated via McWeeny’s (or Pople’s) quantum‐mechanical formalism, the point‐dipole model gives rise to an empirical correlation with experimental 1H‐NMR chemical shifts in a wide range of condensed, benzenoid hydrocarbons which is as good as that obtained when predictions of other, ostensibly more refined, ring‐current theories — as well as calculations effected by application of Blustin’s very recent ’’π‐bond’’ model — are regressed against the same experimental data.