Synthesis and electrochemistry of dimanganese(II) complexes of phenol-based dinucleating ligands with four methoxyethyl chelating arms

Abstract

Dimanganese(II) complexes [Mn 2 (bonp)(PhCO 2 ) 2 ]PF 6 (1) and [Mn 2 (bocp)(PhCO 2 ) 2 ]PF 6 (2) were synthesized with p -nitro- and p -chloro-substituted phenol-based dinucleating ligands bonp - [2,6- bis [ bis (2-methoxyethyl)aminomethyl]-4-nitrophenolate anion] and bocp - [4-chloro-2,6- bis [ bis (2-methoxyethyl)aminomethyl]phenolate anion], respectively, with the aim of controlling the redox potentials of the dimanganese center by changing the p -substituents in the dinucleating ligands. Cyclic voltammograms of 1 and 2 showed quasi-reversible oxidation processes, assigned to Mn II Mn II /Mn II Mn III , at 1.17 and 1.00 V vs. Ag/AgCl, respectively. Compared to the previous p -methyl complex [Mn 2 (bomp)(PhCO 2 ) 2 ]PF 6 (3) [bomp – : 2,6- bis [ bis (2-methoxyethyl)aminomethyl]-4-methylphenolate anion] (0.96 V vs. Ag/AgCl), the order of the potentials was 1(-NO 2 ) > 2(-Cl) > 3(-CH 3 ). Thus, the redox potentials of the dimanganese centers were controlled by the p -substituents in the dinucleating ligands.