Abstract
The unsym. diruthenium complexes (bpy)2RuII(m-H2L2-)RuIII(acac)2ClO4 (3ClO4), (pap)2RuII(m-H2L2-)RuIII(acac)2ClO4 (4ClO4), and (bpy)2RuII(m-H2L2-)RuII(pap)2(ClO4)2 (5(ClO4)2) were obtained by way of the mononuclear precursors (bpy)2RuII(H3L-)ClO4 (1ClO4) and (pap)2RuII(H3L-)ClO4 (2ClO4) (bpy = 2,2'-bipyridine, pap = 2-phenylazopyridine, acac- = 2,4-pentanedionate, and H4L = 1,4-diamino-9,10-anthraquinone). Structural characterization by single-crystal x-ray diffraction and magnetic resonance (NMR, EPR) were used to establish the oxidn. state situation in each of the isolated materials. Cyclic voltammetry, EPR, and UV-visible-near-IR (UV-visible-NIR) spectroelectrochem. were used to analyze the multielectron transfer series of the potentially class I mixed-valent dinuclear compds., considering the redox activities of differently coordinated metals, of the noninnocent bridge and of the terminal ligands. Comparison with sym. analogs L'2Ru(m-H2L)RuL'2n (L' = bpy, pap, or acac-) shows that the redox processes in the unsym. dinuclear compds. are not averaged, with respect to the corresponding sym. systems, because of intramol. charge rearrangements involving the metals, the noninnocent bridge, and the ancillary ligands. on SciFinder(R)
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