1 minus sign represents an anionic u complex; R1 and Rz are alkoxyl, hydroxyl, amino, cyano, and halogeno groups, etc.) have been prepared by nucleophilic attack on polynitroaromatic compounds. 2 Since such anionic u complexes were found as intermediates in some aromatic nucleophilic substitution reactions, much attention has been paid to them from mechanistic and theoretical points of view. The electronic structure of ...