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

The diazo coupling reaction between a tetraaza[14]annulene (1) and a series of 4-substituted phenyldiazonium tetrafluoroborates yielded the correspond ing 7,16-disubstituted products. Mass spectra indicate the presence of mole cular ion peaks that substantiate the 7,16-disubstituted products (4); the lack of olefinic proton signals corresponding to the 7,16- position in the H-1 nmr spectra of 4 also show that diazo coupling has taken place. Analysi s of signals corresponding to the methyl groups of 4 in their H-1 and C-13 nmr spectra indicate that the imine-bis-hydrazone form is present for compo unds that do not contain p-methoxyphenyl groups. However, analysis of methy l signals in the nmr specta of compounds 4 containing p-methoxyphenyl group s show that the bis-azo form and the imine-bis-hydrazone form are present t hrough tautomerism. Complexation with nickel(II) ion induces the formation of the bis- azo structure.