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Acid-base properties of Al(III), Ga(III), and In(III) complexes with tert-butyl-substituted thianaphthene-annulated porphyrazine and tetra(2,3-pyrazino)porphyrazine in proton-donor medium (CH2Cl2-CF3COOH) were studied by spectrophotometric titration. The concentration stability constants of the singly protonated complexes were determined. The effects of the metal nature and aromatic heterocyclic fragment on the basicity of meso-nitrogen atoms were analyzed. Negative inductive effect of the sulfur atom in the thianaphthene fragment reduces the basicity of the meso-nitrogen atoms as compared to analogous porphyrazine and phthalocyanine complexes. Acid-base transformations of the thianaphthene-annulated tetra(2,3-pyrazino)porphyrazine involve both meso-nitrogen atoms and those in the pyrazine rings.

Basic properties of tri(4-tert-butylbenzo)[b,g,l](1,2,5-thiadiazolo)[3,4-q]porphyrazine and its Cu complex in the H2SO4-CH3COOH medium were studied by means of spectrophotometric titration. It was found that in going from an acetic acid solution 100% H2SO4 the complete acid-base interaction consecutively involves all the four meso-nitrogen atoms of the porphyrazine macroring, as well as one of the nitrogen atoms of the 1,2,5-thiadiazol fragment. The stability constants of the resulting acid forms were determined and compared with the gas-phase proton affinities calculated by the AM1 method. Annulation of a 1,2,5-thiadiazole fragment to the porphyrazine macroring increases the basicity of the 1,2,5-thiadiazole nitrogen atoms and decreases the basicity of macroring meso-nitrogen atoms.

The effect of tetra-β-phenyl substitution on the acid-base properties of the porphyrazine macroring was studied by theoretical and experimental methods.

Indium complex of 13,17-dibutyl-2,3,7,8,12,18-hexamethyl-5-azaporphyrin (Cl)InMAP was synthesized, and acid-base interactions of the meso-nitrogen atoms in (Cl)InMAP and its diaza analog (Cl)InDAP with acetic and trifluoroacetic acids were studied by 1H NMR and electronic spectroscopy. Depending on the medium, the complexes and proton-donor species HA give rise to acid solvates >N⋅⋅⋅(HA)n which are converted to final acid-base interaction products, H-complexes >N⋅⋅⋅H+⋅⋅⋅A−(HA)m or ionic associates >NH+⋅⋅⋅A−(HA)l , as the acidity of the medium rises. In acetic acid solution, the acid solvates derived from more basic (Cl)InMAP exist in equilibrium with the H-associates (pK a1 = 4.45±0.03). From (Cl)InDAP, the corresponding H-associates are formed only in the presence of H2SO4 (pK a1 = 2.10±0.03). In more polar media (solutions of trifluoroacetic acid in methylene chloride), ionic associates are formed, which involve one [(Cl)InMAP, pK 1 = 2.46±0.02] or two meso-nitrogen atoms [(Cl)InDAP, pK 1 = 2.11±0.03, pK 2 = 0.41±0.04).

Stability constants were determined for acid forms of octa(4-chloromethylphenyl)-, octa(4-bromophenyl)-, and octa(4-nitrophenyl)tetraazaporphyrins, formed by acid-base interactions in H2SO4-CH3COOH mixtures. The probability of formation of each form depends not only on the electronic structure of the molecule, but also on the composition and properties of the medium.

The acid-base interaction of chloro(octaphenyltetraazaporphinato)erbium(III), (acetylacetonato)(octaphenyltetraazaporphinato)erbium(III), and (acetylacetonato)(octaphenyltetraazaporphinato)dysprosium(III) in AcOH and in AcOH-benzene and AcOH-H2SO4 systems involves one meso-nitrogen atom of the complexes; the stability constants of the resulting acid forms were estimated. The solvoprotolytic dissociation of the complexes in the AcOH-H2SO4 system was studied, its kinetic parameters were determined, and some suggestions as to the dissociation mechanism were made.

Stability of chloro(octaphenyltetraazaporphinato)indium(III) and chloro(2,8,12,18-tetrabutyl-3,7,13,17-tetramethyl-5,15-diazaporphinato)indium(III) in 90-98 % aqueous sulfuric acid was studied. Kinetic parameters of solvoprotolytic dissociation of the complexes were determined, and a mechanism of the reaction was proposed. Diaza substitution results in more stable complexes than tetraaza substitution. The state of chloro(2,8,12,18-tetrabutyl-3,7,13,17-tetramethyl-5,15-diazaporphinato)indium(III) in a proton-donor medium was studied to show that the acid-base interaction involves one by one two meso-nitrogen atoms. Dissociation constants of the resulting acid forms were determined.

Tetraphenyltetraazaporphyrin was reacted with bromine in trifluoroacetic acid to obtain tetrakis(4-bromophenyl)tetraazaporphyrin. The latter forms with pyridine and dimethyl sulfoxide proton-transfer complexes which differ from each other by the degree of proton transfer from the NH acid to base.