DSpace
 

DSpace at IIT Bombay >
IITB Publications >
Article >

Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/11658

Title: 3,6-bis(2 '-pyridyl)pyridazine (L) and its deprotonated form (L-H+)(-) as ligands for {(acac)(2)Run+} or {(bpy)(2)Rum+}: investigation of mixed valency in [{(acac)(2)Ru}(2)(mu-L-H+)](0) and [{(bpy)(2)Ru}(2)(mu-L-H+)](4+) by spectroelectrochemistry and EPR
Authors: GHUMAAN, S
SARKAR, B
PATRA, S
PARIMAL, K
VAN SLAGEREN, J
FIEDLER, J
KAIM, W
LAHIRI, GK
Keywords: creutz-taube ion
tridentate bridging ligand
excited-state properties
cis-dihydrido complexes
crystal-structure
electrochemical properties
electron-transfer
ruthenium(ii) complexes
diruthenium complexes
polynuclear complexes
Issue Date: 2005
Publisher: ROYAL SOC CHEMISTRY
Citation: DALTON TRANSACTIONS, (4), 706-712
Abstract: Crystallographically characterised 3,6-bis(2'-pyridyl) pyridazine (L) forms complexes with {(acac)(2)Ru} or {(bpy)(2)Ru2+} via one pyridyl-N/pyridazyl-N chelate site in mononuclear Ru-II complexes (acac)(2)Ru(L), 1, and [(bpy)(2)Ru(L)] (ClO4)(2), [3] (ClO4)(2). Coordination of a second metal complex fragment is accompanied by deprotonation at the pyridazyl-C-5 carbon {L --> (L-H+)} to yield cyclometallated, asymmetrically bridged dinuclear complexes [(acac)(2)Ru-III (mu-L-H+) Ru-III (acac)(2)] (ClO4), [2] (ClO4), and [(bpy)(2)Ru-II (mu- L-H+) Ru-II (bpy)(2)] (ClO4)(3), [4] (ClO4)(3). The different electronic characteristics of the co-ligands, sigma donating acac(-) and pi accepting bpy, cause a wide variation in metal redox potentials which facilitates the isolation of the diruthenium(III) formin [2] (ClO4) with antiferromagnetically coupled Ru-III centres (J = 11.5 cm(-1)) and of a luminescent diruthenium(II) species in [4] (ClO4)(3). The electrogenerated mixed-valent (RuRuIII)-Ru-II states 2 and [4](4+) with comproportionation constants K-c > 10(8) are assumed to be localised with the Ru-III ion bonded via the negatively charged pyridyl-N/pyridazyl-C-5 chelate site of the bridging (L-H+)(-) ligand. In spectroelectrochemical experiments they show similar intervalence charge transfer bands of moderate intensity around 1300 nm and comparable g anisotropies (g(1)-g(3) approximate to 0.5) in the EPR spectra. However, the individual g tensor components are distinctly higher for the pi acceptor ligated system [4](4+), signifying stabilised metal d orbitals.
URI: http://dx.doi.org/10.1039/b417530a
http://dspace.library.iitb.ac.in/xmlui/handle/10054/11658
http://hdl.handle.net/10054/11658
ISSN: 1477-9226
Appears in Collections:Article

Files in This Item:

There are no files associated with this item.

View Statistics

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! DSpace Software Copyright © 2002-2010  Duraspace - Feedback