
%0 Journal Article
%A Calder, KE 
%A Calvert, RL 
%A Lukins, PB 
%A Ritchie, GLD 
%T Magnetic anisotropies and relative aromaticities of pyrrole, pyrazole, imidazole and their N-methyl derivatives
%J Australian Journal of Chemistry
%D 1981/09/01
%V 34
%N 9
%P 1835-1844
%K 
%R https://doi.org/10.1071/CH9811835
%U https://www.publish.csiro.au/paper/CH9811835 
%X Experimental dipole moments, molar Kerr constants and molar Cotton-Mouton constants at 298 K and 633 nm are reported for pyrrole, pyrazole, imidazole and their N-methyl derivatives as solutes in dioxan. Analysis of the Kerr-effect data yields the effective polarizability anisotropies which are used to evaluate the molecular magnetic anisotropies from the Cotton-Mouton constants. The magnetic criterion of aromaticity is applied by estimating for each molecule the non-local contribution to the out-of-plane component of the magnetizability and the magnetic anisotropy. Electron delocalization in these molecules is significantly less than that exhibited by benzene: pyrrole and N-methylpyrrole, c. 70%; pyrazole and N-methylpyrazole, c. 65%; imidazole and N-methyl-imidazole, c. 60%. Approximately one-third of the observed magnetic anisotropy arises from localized contributions. 
