Pyrazines metal complexes

Given a suitable potential bridging ligand (Y), such as 4,4 -bipyridyl, 4-cyanopyridine, or pyrazine, metal complexes can be used as ligands for pentacyanoferrate(II) as in equation (1). The value of kf is about a thousand... 

On the other hand, the formation of metal complexes of bothpyrido-[2,3-f ]- and -[3,4-f ]-pyrazines is widely reported (e.g. 52JCS4985, 54JCS505). 

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... 

Mixed valency occurs in minerals (e.g. 63 ), metal-chain compounds, dimers and oligomers and metal complexes, and even in organic and biological systems (Brown, 1980 Day, 1981). Among the dimeric and oligomeric metal complexes exhibiting mixed valency, the pyrazine-bridged Ru (II, III) ammine complex. 

The diazines also form metal complexes. Thus, pyrazine forms tetrahedral and octahedral complexes with Co11 and other transition metals it functions as a monodentate and also as a bidentate bridging ligand to give polymeric complexes. The stability of these complexes is increased by back-bonding. 

Pyrazine derivatives were again popular as ligands in crystallographic studies of transition metal complexes. These complexes included silver(I) alkylpyrazine sulfonates 83 <07IC7299>, tetrakis[3-(pyrazin-2-yloxy)pyridinc-AiVJdithiocyanatomanganese <07AX(E)m441>,... 

Fig. 6. Formula of a decanuclear Ru " " metal complex with 2,3-bis (2 -pyridyl) pyrazine (dpp) bridging ligands and 2,2 - bipyridine (bpy) peripheral ligands, and the corresponding scheme (Fig. 2b).

An large number of pyrazines were subjected to X-ray crystallographic analysis. Those in the realm of metal complexes included [/i-2,3,5,6-tetrakis(2-pyridyl)pyrazine]bis[chloroplatinum(II)] bis[trichloro(dimethyl sulfoxide-ir5)platinate(II)] 152 <03AX(E)411>, tetraaqua-1,2,4,5-benzenetetracarboxylato(pyrazine)dicobalt(II) dihydrate <03AX(E)841>, polymeric... 

Electrochemical characterization has been performed in acetonitrile solution on a great variety of dendrimers built with metal complexes as branching centers in the whole structure [16]. An interesting example is that represented by the decametallic dendrimers 30-32, where the metal centers are linked by bridging ligands made of two, closely connected bis-chelating units such as 2,3-dpp (2,3-dpp = 2,3-bis(2-pyridyl)pyrazine) [76, 78]. In the dendritic species, each mononuclear component brings its own redox properties, more or less affected by intercomponent inter-... 

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