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RESEARCH PRODUCT

Synthesis, physicochemical and electrochemical properties of metal–metal bonded ruthenium corrole homodimers

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Abstract Two diruthenium(III,III) corrole dimers, [(Et 6 Me 2 Cor)Ru] 2 and [(Me 6 Et 2 Cor)Ru] 2 , where Et 6 Me 2 Cor and Me 6 Et 2 Cor are the 2,3,8,12,17,18-hexaethyl-7,13-dimethylcorrole and 8,12-diethyl-2,3,7,13,17,18-hexamethylcorrole trianions, respectively, were synthesized and characterized as to their spectroscopic and electrochemical properties. They exhibit up to three oxidations and two reductions by cyclic voltammetry in CH 2 Cl 2 or pyridine containing 0.1 M TBAP, almost all of which are electrochemically reversible on the voltammetric and/or thin-layer spectroelectrochemical timescale. The two reductions and the first two oxidations involve one-electron transfer processes which are separated from each other by 770–880 mV upon reduction and by 350–420 mV upon oxidation. The UV–vis spectroelectrochemical data suggest that the first two one-electron oxidations occur at the diruthenium metal centers while the third oxidation (seen only in CH 2 Cl 2 ) is proposed to be macrocycle-based, leading to the formation of a Ru 2 (IV,IV) corrole species. The formation of a Ru(III,IV) complex after abstraction of one electron is also suggested by the rhombic ESR spectrum of singly oxidized [(Me 6 Et 2 Cor)Ru] 2 at 77 K. The first one-electron reduction is also assigned as metal-centered and leads to the formation of a Ru 2 (III,II) complex. Finally, a comparison of electrochemical properties between the investigated diruthenium(III,III) corroles and an earlier characterized diruthenium(II,II) octaethylporphyrin, [(OEP)Ru] 2 , is presented.