Tetraarylammonium salts - synthesis, properties and emerging use.

The chemistry of tetraarylammonium salts, first explored in the 1960s Soviet Union, has long been a dormant field of research. This is owing to the inherent difficulty in adding a fourth benzene ring to the nitrogen atom of the sterically demanding and low-nucleophilicity triphenylamine molecule. Only recently have new developments in synthetic methodology made access to tetraarylammonium salts less of a tour de force, and first applications are beginning to emerge. As a consequence, the number of publications in this field of research is growing. The review covers the complete field of research, from the beginnings to the present day.