Protonation and solvation effects in the reaction of zinc 1,2,3,7,8,12,13,17,18,19-Decamethylbiladien-<Emphasis Type="Italic">a,c</Emphasis> complex formation

The reactions of protonated (H₄L²⁺) and free (H₂L) forms of the ligand 1,2,3,7,8,12,13,17,18,19-decamethylbiladien-a,c with zinc(II) acetate in dimethyl sulfoxide was studied by the spectrophotometric method. It was found that the mononuclear complex ZnL] is formed in the studied systems. Constants of its formation were determined from the spectral data. Unlike H₂L, the protonated H₄L²⁺] form has extremely low reactivity, because the initial stages of the complex formation mechanisms of the free and protonated forms of the ligand are different. Regularities of the solvent nature influence on the free energy of formation of biladien chelates were revealed.