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/10054/4011

Title: Probing mixed valence in a new tppz-bridged diruthenium(III,II) complex{(mu-tppz)[Ru(bik)Cl]2}(3+) (tppz=2,3,5,6-tetrakis(2-pyridyl)pyrazine, bik=2,3,5,6-tetrakis(2-pyridyl)pyrazine, bik=2,2'-bis(1-methylimidazolyl)ketone): EPR silence, intervalence absorption, and v(CO) line broadening
Authors: KOLEY, M
SARKAR, B
GHUMAAN, S
BULAK, E
FIEDLER, J
KAIM, W
LAHIRI, GK
Keywords: creutz-taube ion
electron-transfer rates
2,3,5,6-tetrakis(2-pyridyl)pyrazine tppz
crystal-structures
ligand 2,3,5,6-tetrakis(2-pyridyl)pyrazine
spectroelectrochemical properties
coordination chemistry
ruthenium complexes
dinuclear
metal
Issue Date: 2007
Publisher: AMER CHEMICAL SOC
Citation: INORGANIC CHEMISTRY, 46(9), 3736-3742
Abstract: The complex dication of the diruthenium(II) compound {(mu-tppz)[Ru(bik)Cl](2)}(ClO4)(2) can be oxidized and reduced in two one-electron steps each. In CH3CN/0.1 M Bu4NPF6, the odd-electron intermediates{(mu-tppz)[Ru(bik)Cl](2)}(n+), n = 1 and 3, have comproportionation constants of 7 x 10(8) and 1 x 10(5), respectively. Both exhibit near-infrared absorptions, in the case of n = 3 the 1640 nm band (epsilon = 1200 M-1 cm(-1), Delta nu(1/2) = 1560 cm(-1)) is attributed to an intervalence charge-transfer transition. While the mixed-valent intermediate (n = 3) is EPR silent even at 4 K, the n = 1 form shows g(II) 2.005 and g(perpendicular to) 1.994 at that temperature, signifying a diruthenium(II) complex of the tppz(center dot-) radical anion. The variation of energy and intensity of nu(CO) and of the ring vibration band around 1590 cm(-1) has been monitored not only for {(mu-tppz)[Ru(bik)Cl](2)}(n+), n = 0-4, but also for the mononuclear {(tppz)Ru(bik)Cl}(n+), n = 0-2. In the dinuclear complex the carbonyl stretching bands of the spectator ligand bik are shifted by about 15 cm(-1) on each one-electron-transfer step, increasing with the positive charge. The mixed-valent {(mu-tppz)[Ru(bik)Cl](2)}(3+) shows a perceptibly broader nu(CO) band, suggesting incomplete valence averaging (partial localization).
URI: http://dx.doi.org/10.1021/ic0700102
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4011
http://hdl.handle.net/10054/4011
ISSN: 0020-1669
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