Mechanistic Information on the Reversible Binding of NO to Selected Iron(II) Chelates from Activation Parameters
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- 作者：Thorsten Schneppensieper ; Alicja Wanat ; Gra
//pubs.acs.org/images/entities/zdot.gif" border="0">yna Stochel ; and Rudi van Eldik
- 刊名：Inorganic Chemistry
- 出版年：2002
- 出版时间：May 6, 2002
- 年：2002
- 卷：41
- 期：9
- 页码：2565 - 2573
- 全文大小：103K
- 年卷期：v.41,no.9(May 6, 2002)
- ISSN：1520-510X
文摘
Mechanistic insight on the reversible binding of NO to FeII chelate complexes as potential catalysts for the removalof NO from effluent gas streams has been obtained from the temperature and pressure parameters for the "on"and "off" reactions determined using a combination of flash photolysis and stopped-flow techniques. These parametersare correlated with those for water exchange reactions on the corresponding FeII and FeIII chelate complexes, fromwhich mechanistic conclusions are drawn. Small and positive 
BORDER=0 >V
values are found for NO binding to and releasefrom all the selected complexes, consistent with a dissociative interchange (Id) mechanism. The only exception inthe series of studied complexes is the binding of NO to [FeII(nta)(H2O)2]-. The negative volume of activation observedfor this reaction supports the operation of an Ia ligand substitution mechanism. The apparent mechanistic differencescan be accounted for in terms of the electronic and structural features of the studied complexes. The resultsindicate that the aminocarboxylate chelates affect the rate and overall equilibrium constants, as well as the natureof the substitution mechanism by which NO coordinates to the selected complexes. There is, however, no simplecorrelation between the rate and activation parameters and the selected donor groups or overall charge on theiron(II) complexes.
BORDER=0 >V values are found for NO binding to and releasefrom all the selected complexes, consistent with a dissociative interchange (Id) mechanism. The only exception inthe series of studied complexes is the binding of NO to [FeII(nta)(H2O)2]-. The negative volume of activation observedfor this reaction supports the operation of an Ia ligand substitution mechanism. The apparent mechanistic differencescan be accounted for in terms of the electronic and structural features of the studied complexes. The resultsindicate that the aminocarboxylate chelates affect the rate and overall equilibrium constants, as well as the natureof the substitution mechanism by which NO coordinates to the selected complexes. There is, however, no simplecorrelation between the rate and activation parameters and the selected donor groups or overall charge on theiron(II) complexes.