Abstract: Electrophilic aromatic nitration of various arenes (ArH) is shown to be critically dependent on labile charge-transfer complexes derived from N-nitropyridinium cations. The electrophiles XPyN02+, with X= CN, C02CH3, C1, H, CH3, and OCH3, form a highly graded series of electron acceptors that produce divers [ArH, XPyN02+] complexes, with charge- transfer excitation energies (hvcr) spanning a range of almost 50 kcal mol-'. The latter ...
