Thermodynamic Basicity Constants of Highly Substituted Manganese Porphyrazines and Their Connection to the Structure of Molecules

Thermodynamic equilibrium constants of protonation of (acetato)(octakis)(4-tert-butylphenyl)- and (acetato)(octakis(3-trifluoromethylphenyl)tetraazaporphynato)manganese(III) in a trifluoroacetic acid–dichloromethane medium are determined via spectrophotometric titration using Hammett acidity function H0 for a mixed solvent. The effect of the higher basicity of the mono-protonated forms against that of the neutral forms is established and interpreted using literature data on tetraazaporphyrin analogs. The role of functional substitution and the electronic structure of coordination centers in the acid–base behavior of porphyrazine complexes is determined. The obtained data are important for developing the theory of reactivity of macroheterocyclic compounds and creating actual supramolecular 2D and 3D structures based on porphyrazines.