Charge-Transfer Activation of Electron Donor-Acceptor Complexes and Their Role in Electrophilic Aromatic Substitution

Abstract

Electron donor-acceptor or EDA complexes are common precursors leading to a variety of organic reactions, as indicated by the appearance of characteristic charge-transfer absorption bands. Structural effects of HOMO-LUMO interactions extant in donor-acceptor pairs, established by X-ray crystallography, are critical to the charge-transfer excitation of various types of weak molecular complexes in which time-resolved picosecond spectroscopy identifies the nature of charge-transfer ion pairs. Their relevance to the transition state description of electrophile/nucleophile interactions is underscored in the detailed study of electrophilic aromatic nitration.