The preparation and properties of a series of 1,2,5-triazapentadienium salts

Abstract

A series of 1,2,5-triazapentadienium salts has been made by the condensation of ammonium salts with monohydrazones of 1,2-dicarbonyl compounds. Their u.v., ¹H, ¹³C, and variable-temperature n.m.r. spectra are compared with those of some related salts. These studies indicate that the interaction of N-phenyl substituents with the conjugated system is more efficient at the 1- than at the 5-position. Deuterium exchange occurs at the 3-position, but attempts to observe substitution reactions with other electrophiles failed. Displacement of the terminal amino-function takes place by reaction of N-nucleophiles at the 4-position.