Ruthenium Complexes of Quinone Related Ligands: A Study of the Electrochemical Properties of 2-Aminothiophenolatobis(2,2‘-Bipyridine)Ruthenium(II)

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Abstract
Electrochemical properties of the newly synthesized 2-amino thiophenolatobis(2,2'-bipyridine)ruthenium(II) [Ru(bpy)(2)(NH(2).S)cat](+) (bpy = 2,2'-bipyridine, (NH(2).S) = 2-aminothiophenolate) are reported, using microelectrode, disk electrode, rotating disk electrode cyclic voltammetry, spectroelectrochemistry, and differential pulse voltammetry. The results are compared with the electrochemical properties of the previously studied [Ru(II)(bpy)(2)LL](n)()(+) compounds, where LL are 1,2-dihydroxybenzene (O.O), 2-aminophenol (NH(m)().O), and 1,2-diaminobenzene (NH(m)().NH(m)()). These ligands can exist in protonated (m = 2) or deprotonated (m = 1) forms. By means of cyclic voltammetry, the deprotonated [Ru(II)(bpy)(2)(NH.S)](0) displayed a series of one-electron reversible redox waves, consistent with the previously observed results for the [Ru(II)(bpy)(2)LL](n)()(+) complexes. However, the reversible waves observed for protonated [Ru(II)(bpy)(2)(NH(2).S) cat](+) are inconsistent with the irreversible waves observed for protonated [Ru(II)(bpy)(2)LL](n)()(+) complexes. An ECE mechanism is proposed to account for these differences and is used to interpret and simulate the cyclic voltammograms (CV)s of [Ru(II)(bpy)(2)(NH(2).S)cat](+) in organic solvents.