
TY  - JOUR
A1  - Calder, KE 
A1  - Calvert, RL 
A1  - Lukins, PB 
A1  - Ritchie, GLD 
T1  - Magnetic anisotropies and relative aromaticities of pyrrole, pyrazole, imidazole and their N-methyl derivatives
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1981
VL  - 34
IS  - 9
SP  - 1835
EP  - 1844
KW  - 
UR  - https://doi.org/10.1071/CH9811835 
N2  - 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. 
ER  -

