“…Several other examples of peri interactions may be found among disubstituted naphthalenes. The observed dipole moment of 1,8-dichloronaphthalene is 2.88 D. (437). These are considerably lower than the calculated moments, assuming that the molecules are planar and that the dipole vectors act along the pert-bond axes (/icaicd for l,8-Ci0H6Cl2, 3.18 D.; for 1,8-Cio-H6(N02)2, ~8.0 D.).…”