Title
A pulsed EPR and DFT investigation of the stabilization of coordinated phenoxyl radicals in a series of cobalt Schiff-base complexes
Author
Faculty/Department
Faculty of Sciences. Chemistry
Faculty of Sciences. Physics
Publication type
article
Publication
Stuttgart ,
Subject
Physics
Chemistry
Source (journal)
Applied magnetic resonance. - Stuttgart
Volume/pages
37(2010) :1/4 , p. 289-303
ISSN
0937-9347
ISI
000272173500022
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
We recently demonstrated how the aerobic addition of acetic acid to N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamino CoII, [Co(1)], leads to the formation of an unusual coordinated CoIII-phenoxyl radical. In this work, some of the structural aspects associated with the Schiff-base-derived ligand (1) that are crucial for the acid-mediated formation of the phenoxyl radical are investigated. For comparison with [Co(1)], we therefore studied the influence of acetic acid on two complexes: (1) the N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-ethane-diamino CoII complex, [Co(2)], that lacks the cyclohexyl group of [Co(1)], and (2) the N′-disalicylidene-ethylenediamine CoII salen complex, [Co(3)], that lacks both the tertiary butyl groups and the cyclohexyl groups. It is shown that the cyclohexyl group of [Co(1)] is not involved in the formation or stabilization of the phenoxyl radical, whereas the tertiary butyl groups of [Co(1)] play a crucial role. In addition, the characteristics of the phenoxyl radical, formed after aerobic addition of acetic acid to [Co(2)], are analyzed in detail by pulsed electron paramagnetic resonance, in combination with isotopic labeling. The experimental data are compared to density functional theory computations and to previous data on the acid-mediated phenoxyl radical of [Co(1)].
E-info
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000272173500022&DestLinkType=RelatedRecords&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000272173500022&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000272173500022&DestLinkType=CitingArticles&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
Handle