Pyrazine, ruthenium complexes

A more subtle effect of 7i-bonding is seen in ruthenium complexes of pyrazine. We saw in Fig. 2-20 that co-ordination of a pyrazinium cation to a ruthenium(m) centre resulted in an increase in its acidity. However, co-ordination to a ruthenium(n) centre results in a decrease in acidity. The lower oxidation state ruthenium(n) centre is stabilised by back-... 

Interest continues in pyrazine-bridged polymeric ruthenium complexes. Following an earlier communication,48 further details have been given of a general synthetic route to pyrazine-bridged Ru11 bipyridyl complexes (equations 10 and ll).49 Employing the reaction of Ru—N02 complexes to yield Ru—NO, in combination with the... 

Mixed Oxidation State Ruthenium. In view of the growing number of mixed valence state ruthenium complexes reported, especially Ru compounds, all the pertinent references are collected in this section. The new pyrazine-bridged... 

Pseudo-first-order rate constants (k J for the reaction between metal ruthenium complex [Ru(NH3)5pz] + (pz = pyrazine) and oxidant S20g (peroxydisul-... 

Alternatively, arene displacement can also be photo- rather than thermally-induced. In this respect, we studied the photoactivation of the dinuclear ruthenium-arene complex [ RuCl (rj6-indane) 2(p-2,3-dpp)]2+ (2,3-dpp, 2,3-bis(2-pyridyl)pyrazine) (21). The thermal reactivity of this compound is limited to the stepwise double aquation (which shows biexponential kinetics), but irradiation of the sample results in photoinduced loss of the arene. This photoactivation pathway produces ruthenium species that are more active than their ruthenium-arene precursors (Fig. 18). At the same time, free indane fluoresces 40 times more strongly than bound indane, opening up possibilities to use the arene as a fluorescent marker for imaging purposes. The photoactivation pathway is different from those previously discussed for photoactivated Pt(IV) diazido complexes, as it involves photosubstitution rather than photoreduction. Importantly, the photoactivation mechanism is independent of oxygen (see Section II on photoactivatable platinum drugs) (83). 

Kinetic parameters k, often also and AS, occasionally AV ) for formation and dissociation of several pentacyanoferrate(II) complexes [Fe(CN)5L]" have been established. Ligands L include several S- and A-donor heterocycles,4-methyl- and 4-amino-pyridines, a series of alkylamines, 3- and 4-hydroxy- and 3- and 4-methoxy-pyridines, several amino acids, nicotinamide, " 4-pyridine aldoxime, 3-Me and 3-Ph sydnones, several bis-pyridine ligands,neutral, protonated, and methylated 4,4 -bipyridyl, 1,2-bis(4-pyridyl)ethane and traTO-l,2-bis0-pyridyl)ethene, pyrazine- 4,4 -bipyridyl- and bis(4-pyridyl)ethyne-pentaammine-cobalt(III), edta-ruthenium(III), and pentaammineruthenium-(II)and-(III) complexes of... 

Pyridine-based ligands which have been used for dendrimers are 2,2-bipyridine (bpy) 17,2,3-bis(2-pyridyl)pyrazine (2,3-dpp) 18 and its monomethylated salt 19, and 2,2 6, 2"-terpyridine 20. Their transition metal complexes possessing dendritic structures were first reported in the collaborative work of Denti, Campagne, and Balzani whose divergent synthetic strategy has led to systems containing 22 ruthenium centers. - The core unit is [Ru(2,3-dpp)3] 21 which contains three... 

ESCA spectra have been recorded for a series of pyrazine-bridged ruthenium dimers including [(NH3)5Ru(pyz)Ru(NH3)5]s H and [(bipy)2ClRu(pyz)RuCl(bipy)2]3+.50 The data show that both Ru and Ruin are present in those complexes although the metal sites are equivalent. The speed with which ESCA monitors electron distribution (ca. 10"17 s) would seem to make it an excellent spectrosocpic tool for such valence-state assignments. 

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