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Non-innocent behaviour of ancillary and bridging ligands in homovalent and mixed-valent ruthenium complexes [A(2)Ru(mu-L)RuA(2)](n), A=2,4-pentanedionato or 2-phenylazopyridine, L2-=2,5-bis(2-oxidophenyl)pyrazine

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Title Non-innocent behaviour of ancillary and bridging ligands in homovalent and mixed-valent ruthenium complexes [A(2)Ru(mu-L)RuA(2)](n), A=2,4-pentanedionato or 2-phenylazopyridine, L2-=2,5-bis(2-oxidophenyl)pyrazine
 
Creator MAJI, S
SARKAR, B
MOBIN, SM
FIEDLER, J
KAIM, W
LAHIRI, GK
 
Subject nuclear magnetic resonance
electron-transfer
spectroelectrochemical properties
polypyridine complexes
crystal-structure
polynuclear complexes
radical complexes
metal-complexes
dinuclear
redox
 
Description Structurally characterised 2,5-bis(2-hydroxyphenyl)pyrazine (H2L) can be partially or fully deprotonated to form the complexes [(acac)(2)Ru(mu-L)Ru(acac)(2)], [1], acac(-) = acetylacetonato 2,4-pentanedionato, [(pap)(2)Ru(mu-L)Ru(pap)(2)](ClO4)(2), [2](ClO4)(2), pap = 2-phenylazopyridine, or [(pap)(2)Ru(HL)](ClO4), [3](ClO4). Several reversible oxidation and reduction processes were observed in each case and were analysed with respect to oxidation state alternatives through EPR and UV-VIS-NIR spectroelectrochemistry. In relation to previously reported compounds with 2,2'-bipyridine as ancillary ligands the complex redox system [1](n) is distinguished by a preference for metal-based electron transfer whereas the systems [2](n) and [3](n) favour an invariant Ru-II state. Accordingly, the paramagnetic forms of [1](n), n = -, 0, +, exhibit metal-centred spin whereas the odd-electron intermediates [2](+), [2](3+) and [3] show radical-type EPR spectra. A comparison with analogous complexes involving the 3,6-bis(2-oxidophenyl)-1,2,4,5-tetrazine reveals the diminished pi acceptor capability of the pyrazine-containing bridge.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2011-08-28T14:24:19Z
2011-12-26T12:58:04Z
2011-12-27T05:47:13Z
2011-08-28T14:24:19Z
2011-12-26T12:58:04Z
2011-12-27T05:47:13Z
2007
 
Type Article
 
Identifier DALTON TRANSACTIONS, (23), 2411-2418
1477-9226
http://dx.doi.org/10.1039/b701511a
http://dspace.library.iitb.ac.in/xmlui/handle/10054/11761
http://hdl.handle.net/10054/11761
 
Language en