An N.M.R. Investigation of Ground-State Polarization of Some Substituted Aromatic Systems

The previously established n.m.r. method for estimating mobile bond orders was applied to the investigation of ground-state polarization of benzene derivatives with ortho or para pairs of +R/-R substituents, naphthalene and five heteroaromatic systems (furan, thiophen, pyrrole, quinoline and pyrazole). Evidence for significant ground-state polarization which is solvent-independent was found in a number of these systems, especially benzene, pyrrole and pyrazole.