Hetarylformazans

The literature data on the synthesis, structure, and properties of formazans containing heteroaromatic substituents (hetarylformazans) have been reviewed and arranged systematically. Hetarylformazans have been compared with arylformazans in characteristic reactions such as oxidation to tetrazolium salts, alkylation, and conversion into stable verdazyl radicals. Special attention has been devoted to the coordination chemistry of formazan-containing systems and to the consideration of the characteristic features introduced by hetaryl substituents into the structure of the complexes. Various aspects of the practical applications of hetarylformazans and their derivatives (dyes, bioindicators, ligands, analytical reagents) and the prospects for the development of their chemistry have been examined.
The bibliography includes 221 references.