Synthesis, Crystal Structure and Electrochemistry ofμ -Acetato-di-μ-hydroxo-bis[(l, 4, 7-triazacyclononane)ruthenium(III)]-tris-iodide. Characterization of Some Ru(II)—Ru(III) Mixed Valence Species

Abstract

A series of mononuclear complexes of ruthenium containing the cyclic triamine ligand 1.4.7-tri-azacyclononane ([9]aneN3 = L; C6h15n3) have been prepared: [Ru11L (dmso)2Cl]Cl (dmso = dimethyl sulfoxide), [Ru111LX3] (X = Cl-, Br-), [RuL2](PF6)2, [RuL(C2O4)I]. Hydrolyses of RuLC13 under a variety of reaction conditions afford dinuclear species: [Ru1112L2(μ-OH)2(μ-CH3C02)]I3 H2O, [Ru1112L2(μ-OH)2Cl2](PF6)2, and the mixed-valence species [ru2L2(μ-C1)3](PF6)2. The complex [ru2l2(μ-oh)2(μ-CH3CO2)]I3 • H2O has been characterized by a single-crystal X-ray diffraction study. The compound crystallizes in the monoclinic space group P21, /c with a = 14.70(1) A, b = 19.00(1) A, c = 9.714(7) A, β= 99.62(7)°, and V = 2674 A3, dcalcd = 2.37 g cm-3 for Z = 4, and mol wt 952.3. The structure was solved by direct methods using 2519 unique reflections with I>2σ(I). Final residuals were R1= 0.0615 and R2= 0.075. The structure consists of μ -hydroxo- and μ -acetato-bridged dinuclear cations and iodide anions. The observed diamagnetism and a short Ru-Ru bond distance of 2.572(3) A are indicative of a Ru—Ru single bond. The electrochemical properties of [Ru2L2(μ-OH)2(μ-CH3C02)]3+ and [ru2l2(μ-c1)3]2+ have been investigated by cyclic voltammetry, and by coulometry. Two one-electron redox processes have been identified for both complexes the first of which exhibits a reversible wave, whereas the second wave at more negative potentials is irreversible. The blue mixed valence species [Ru2L2(μ-OH)2(μ-CH3C02)]2+ has been characterized in solution. © 1984, Walter de Gruyter. All rights reserved.