Protonation and solvation effects in the reaction of zinc 1,2,3,7,8,12,13,17,18,19-Decamethylbiladien-a,c complex formation

The reactions of protonated (H 4 L 2+ ) and free (H 2 L) 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 H 2 L, the protonated [H 4 L 2+ ] 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.