Electron transfer in the thermal and photochemical activation of electron donor-acceptor complexes in organic and organometallic reactions

This chapter highlights electron transfer in the thermal and photochemical activation of electron donor–acceptor complexes in organic and organometallic reactions. The chapter is intended as a follow-up to the seminal reviews that originally pointed out the importance of charge-transfer complexes in organic reactions. Following a prolonged hiatus, the advent of direct methods, involving time-resolved (laser) spectroscopy, has triggered a renewed interest in charge-transfer complexes as reactive intermediates. The chapter emphasizes the generality of the charge-transfer concept by demonstrating the ways in which the methodology can be applied to various organic and organometallic processes. The review of the chapter is mainly concerned with research carried out in laboratories. This chapter illustrates that aromatic nitration represents the prototypical system for illustrating the ways in which the detailed study of charge-transfer activation allows a unifying theme to be developed for electrophilic aromatic substitution as an important aspect of physical organic chemistry. © 1994 Academic Press Limited