title: Soluble redox-active polymetallic chains [{Ru0(CO)(L)(bpy)}m](n) (bpy = 2,2'-bipyridine, L = PrCN, Cl-; m = 0, -1): electrosynthesis and characterization.
abstract: Electrochemical and spectroelectrochemical techniques were employed to study in detail the formation and so far unreported spectroscopic properties of soluble electroactive molecular chains with nonbridged metal-metal backbones, namely, [{Ru(0)(CO)(PrCN)(bpy)}(m)](n) (m = 0, -1) and [{Ru(0)(CO)(bpy)Cl}(m)](n) (m = -1, -2; bpy = 2,2'-bipyridine). The precursors cis-(Cl)-[Ru(II)(CO)(MeCN)(bpy)Cl(2)] (in PrCN) and mer-[Ru(II)(CO)(bpy)Cl(3)](-) (in tetrahydrofuran (THF) and PrCN) undergo one-electron reductions to reactive radicals [Ru(II)(CO)(MeCN)(bpy(*-))Cl(2)](-) and [Ru(II)(CO)(bpy(*-))Cl(3)](2-), respectively. Both [bpy(*-)]-containing species readily electropolymerize on concomitant dissociation of two chloride ligands and consumption of a second electron. Along this path, mer-to-fac isomerization of the bpy-reduced trichlorido complex (supported by density functional theory calculations) and a concentration-dependent oligomerization process contribute to the complex reactivity pattern. In situ spectroelectrochemistry (IR, UV/vis) has revealed that the charged polymer [{Ru(0)(CO)(bpy)Cl}(-)](n) is stable in THF, but in PrCN it converts readily to [Ru(0)(CO)(PrCN)(bpy)](n). An excess of chloride ions retards this substitution at low temperatures. Both polymetallic chains are completely soluble in the electrolyte solution and can be reduced reversibly to the corresponding [bpy(*-)]-containing species.
authors: Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, United Kingdom. f.hartl@reading.ac.uk
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