Investigation of unsubstituted porphyrazine by proton NMR and the structure of porphyrazine ligands

Abstract

The proton NMR spectra of unsubstituted porphyrazine (tetraazaporphine) and of its Zn complex in pyridine-D₅ and in CF₃COOD have been obtained for the first time. The observed strong deshielding of the pyrrole hydrogen atoms of these compounds compared with porphyrins indicates the existence of strong intramolecular hydrogen bonds with neighboring pyrrolenic nitrogen atoms. An unsymmetrical bridge structure is proposed for the reaction center of unsubstituted porphyrazine with significantly ionized N−H bonds. It is suggested that a symmetrical bridge structure almost completely ionized, may exist only in the presence of such strong electron-accepting substituents as halogen in the pyrrole rings of the porphyrazine macrocycle.

How to Cite
Stuzhin, P. A. Chem. Heterocycl. Compd. 1997, 33, 1185. [Khim. Geterotsikl. Soedin. 1997, 1364.]

For this article in the English edition, see DOI https://doi.org/10.1007/BF02290867