A pulse radiolysis study of the rate of ligand dissociation from mixed ligand cobalt(II) complexes

Funston, Alison M., McFadyen, W. David and Tregloan, Peter A. (2002) A pulse radiolysis study of the rate of ligand dissociation from mixed ligand cobalt(II) complexes. Journal of the Chemical Society, Dalton Transactions, 9: 2053-2060. doi:10.1039/b107392n


Author Funston, Alison M.
McFadyen, W. David
Tregloan, Peter A.
Title A pulse radiolysis study of the rate of ligand dissociation from mixed ligand cobalt(II) complexes
Journal name Journal of the Chemical Society, Dalton Transactions   Check publisher's open access policy
ISSN 1472-7781
1470-4358
0300-922X
Publication date 2002
Sub-type Article (original research)
DOI 10.1039/b107392n
Issue 9
Start page 2053
End page 2060
Total pages 8
Language eng
Subject 03 Chemical Sciences
Formatted abstract
The reduction and subsequent reactions of the series of mixed ligand cobalt(III) complex cations, [Co(bipy)3]3+, [Co(phen)3]3+, [Co(en)3]3+, [Co(en)2(bipy)]3+, [Co(en)2(phen)]3+, [Co(en)2(5-NO2-phen)]3+, [Co(en)2(DPPZ)]3+, [Co(bipy)2(NH3)2]3+, [Co(bipy)(NH3)4]3+, [Co(phen)2(NH3)2](ClO4)3]3+ and [Co(phen)(NH3)4]3+, (where bipy is 2,2′-bipyridine, phen is 1,10-phenanthroline, en is ethylenediamine, 5-NO2-phen is 5-nitro-1,10-phenanthroline and DPPZ is dipyrido[3,2-a:2′,3′-c]phenazine) have been studied using pulse radiolysis. The crystal structures of the mixed ligand complexes [Co(bipy)2(NH3)2](ClO4)3, [Co(bipy)(NH3)4]Cl0.5(ClO4)2.5, [Co(phen)2(NH3)2](ClO4)3 and [Co(phen)(NH3)4](ClO4)3, have been determined. The mechanism of reduction of the cobalt(III) centre by e−aq has been found to vary depending upon the nature of the ligands present in the complex. When an aromatic ligand is present the formation of a coordinated ligand radical is observed. This decays via intramolecular electron transfer to produce the cobalt(II) complex. The rate constants for the intramolecular electron transfer processes are of the order of 103–104 s−1. The rates of ligand dissociation of bidentate ligands from the resulting cobalt(II) complexes have been determined. The relative rates of the dissociation of the first ligand from the complexes is found to be dependent upon the identity of the ligand and is related to the ligand structure. For the dissociation of the same ligand from related complexes, the electronic structure of the complex becomes a factor.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Institute for Teaching and Learning Innovation Publications
 
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Created: Mon, 13 Sep 2010, 08:59:45 EST by Laura McTaggart on behalf of Centre for Educational Innovation & Technology