Ruthenium mixed-valence

Ruthenium mixed-valence complexes are ubiquitous in coordination chemistry. For this reason, the common oxidation states of ruthenium will be adopted in the following discussion of comproportionation constants. 

The diffusion-limited electrochemical oxidation of V-nitrosamines in an aqueous pH 1.5 buffer was demonstrated at a GCE coated with a film of mixed valence ruthenium oxides, stabilized by cyano crosslinks. This electrode was used in a potentiostatic amperometric detector for FIA and HPLC, to allow the determination of representative N-nitrosamines (278a, 278c and 278d) for 278c, LOD was 10 nM and RSD 2% at 0.80 pM... 

Creutz-Taube ion [bis(pentaammine-ruthenium)pyrazine]D (30) provides an example of this. There is good reason to suppose (in spite of many earlier arguments to the contrary) that this is a fully delocalized mixed-valence system (27). In symmetry, the one-electron levels separated by energy gap 2J are calculated to have b u (bonding) and b (antibonding) symmetry,... 

Increasing attention is being given to the reactivity of ruthenium species which show unusual behavior compared with their Co analogs. Aspects of current interest are mixed valence states, ruthenated proteins to probe electron transfer in them (Chap. 5) and the photochemistry and photophysics of Ru(II) polypyridine eomplexes. 

The compound Ba5[Ru2(0)n] has been synthesized by solid-state reactions of barium carbonate with ruthenium oxide. The X-ray structure shows that it contains peroxide ions and the ruthenium is in the +5 oxidation state, i.e., Ba5[Ru2(02)0g]. The novel mixed-valence Ru — Ru triple perovskites, Ba3M[Ru2(0)9] (M = Li, Na), have been grown from reactive hydroxide fluxes. ... 

In most of the reactions studied, the appearance of biphasic kinetics showed that the full oxidation process is achieved through the stepwise oxidation of one of the metal centers, rendering a mixed-valence species which is further oxidized to the final product. The question arises in Eq. (35) as to the alternative first oxidation of iron or ruthenium. The stoichiometry of the first oxidation step with bridging 4- and 3-cyanopyridines (with the N-atom of py binding to... 

Other mixed-valence metal complexes have been published that display electrochromic behavior, among them bipyridyl ruthenium complexes linked through dioxolene containing bridging ligands, such as 3,3, 4,4 -tetrahydroxybi-phenyl, 3,3",4,4"-tetrahydroxy-p-terphenyl, and 9-phenyl-2,3,7-trihydoxy-6-flu-orone [115,116] (Chart 3). Many of the redox processes that lead to frequently... 

Mixed Ruthenium-tii) and -(m) Complexes.—Interactions of the oxo-centred RuI 1 acetate [Ru30(C02Me)6(Me0H)3]+ and the reduced species [Ru30(C02Me)6 (MeOH)3] with carbon monoxide, sulphur dioxide, and NO have been studied.71 Scheme 5 summarizes the products obtained from the latter mixed-valency complex following carbonylation. Only a monocarbonyl complex is seen to be formed, and the... 

There are several photocatalysts mimicking hydrogenase activity that are not based on metalloporphyrin systems. Among them there are mixed-valence complexes of rhodium or iridium, [41] as well as complex systems encompassing photosensitizers (eg ruthenium complexes) attached to a catalytic bimetallic centre [43], The design of more sophisticated systems approaches that of photosynthetic processes [44],... 

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