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Ruthenium terpyridine complexes incorporating azo-imine based ancillary ligands. Synthesis, crystal structure, spectroelectrochemical properties and solution reactivities

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Title Ruthenium terpyridine complexes incorporating azo-imine based ancillary ligands. Synthesis, crystal structure, spectroelectrochemical properties and solution reactivities
 
Creator MONDAL, B
WALAWALKAR, MG
LAHIRI, GK
 
Subject electron-transfer properties
r = h
transfer excited-states
redox properties
bridging ligand
o-me/cl
spectroscopic characterization
electrochemical properties
photophysical properties
absorption-spectra
 
Description Ruthenium terpyridine complexes of the type [Ru-II(trpy)(L)(X)][ClO4](n) 1-15 [trpy=2,2':6,2"-terpyridine; L=NC5H4N=NC6H4(R), R=H, m-Me, m-Cl, p-Me or p-Cl; X=Cl-, n=1 (1-5); H2O, n=2 (6-10) or OH-, n=1 (11-15)] have been synthesized. The single crystal structures of 1 and 6 were determined. Complex 4 develops in two possible isomeric forms whereas all other complexes stabilise preferentially in one isomeric form. The complexes exhibit strong MLCT bands near 500 nm and ligand based transitions in the UV region. 1-5 exhibit moderately strong emissions at 77 K near 600 nm. The chloro (1-5) and the hydroxo (11-15) complexes display ruthenium(III)-ruthenium(II) couples and three to four successive one-electron ligand based reductions. The aqua-complexes (6-10) exhibit a reversible 2e(-)/2H(+) single-step oxidation process in the pH range 1-5.5 corresponding to the [Ru-II(trpy)(L)(H2O)](2+)-[Ru-IV(trpy)(L)(O)](2+) couple and the potential decreases linearly with increase in pH. The chemical oxidations of 6-10 by an excess of Ce-IV in 0.5 M H2SO4 also lead to the formation of corresponding [Ru-IV(trpy)(L)(O)](2+). The oxo-complexes are stable only in the presence of an excess of Ce-IV, otherwise they catalyse the oxidation of water to dioxygen and convert back into the parent aqua-species. The pseudo first order rate constant of the process [Ru-IV(trpy)(L)(O)](2+)--> [Ru-II(trpy)(L)(H2O)](2+) has been determined.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2011-08-28T17:34:02Z
2011-12-26T12:58:08Z
2011-12-27T05:47:36Z
2011-08-28T17:34:02Z
2011-12-26T12:58:08Z
2011-12-27T05:47:36Z
2000
 
Type Article
 
Identifier JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS, (22), 4209-4217
1470-479X
http://dx.doi.org/10.1039/b005789o
http://dspace.library.iitb.ac.in/xmlui/handle/10054/11800
http://hdl.handle.net/10054/11800
 
Language en