Synthesis and characterization of 7, 16‐bis(phenylazo)tetraaza[14]annulenes

Abstract

AbstractThe diazo coupling reaction between a tetraaza[14]annulene (1) and a series of 4‐substituted phenyl‐diazonium tetrafluoroborates yielded the corresponding 7, 16‐disubstituted products. Mass spectra indicate the presence of molecular ion peaks that substantiate the 7,16‐disubstituted products (4); the lack of olefinic proton signals corresponding to the 7,16‐ position in the 1H nmr spectra of 4 also show that diazo coupling has taken place. Analysis of signals corresponding to the methyl groups of 4 in their 1H and 13C nmr spectra indicate that the imine‐bis‐hydrazone form is present for compounds that do not contain p‐methoxyphenyl groups. However, analysis of methyl signals in the nmr specta of compounds 4 containing p‐methoxyphenyl groups show that the bis‐azo form and the imine‐bis‐hydrazone form are present through tautomerism. Complexation with nickel(II) ion induces the formation of the bis‐ azo structure.