The title complexes were obtained in neutral form (n = 0) as rac (1) and meso isomers (2). 2 was crystallized for X-ray diffraction and its temperature-dependent magnetism studied. It contains two antiferromagnetically coupled ruthenium(III) ions, bridged by the quinizarine dianion QL2- (quinizarine = 1,4-dihydroxy-9,10-anthraquinone). The potential of both the ligand (QL0 → QL4-) and the metal complex fragment combination [(acac)2RuII]2 → {[(acac) 2RuIV]2}4+ to exist in five different redox states creates a large variety of combinations, which was assessed for the electrochemically reversibly accessible 2+, 1+, 0, 1-, 2- forms using cyclic voltammetry as well as EPR and UV-vis-NIR spectroelectrochemistry. The results for the two isomers are similar: Oxidation to 1+ or 2+ causes the emergence of a near-infrared band (1390 nm), without revealing an EPR response even at 4 K. Reduction to 1- or 2 - produces an EPR signal, signifying metal-centered spin but no near-infrared absorption. Tentatively, we assume metal-based oxidation of [(acac)2RuIII(μ-QL-2-)RuIII(acac) 2] to a mixed-valent intermediate [(acac)2Ru III(μ-QL2-)RuIV(acac)2] + and ligand-centered reduction to a radical complex [(acac) 2RuIII(μ-QL·3-)RuIII(acac) 2]- with antiferromagnetic three-spin interaction. © 2008 American Chemical Society.