Thermodynamics and kinetics of as an efficient scavenger for nitric oxide in aqueous solution

2002
journal article
article
53
dc.abstract.enThe edta complex of $Ru^{III}$ reacts very rapidly with NO in aqueous solution at pH=5 to form a stable nitrosyl complex. The results from FT-IR (ATR) and $^{15}\textrm{N}-NMR$ studies clearly support the $NO^{+}$ character of coordinated NO, such that the nitrosyl product can be formulated as $[Ru^{III}(edta)NO]^{+}$. A combination of UV-Vis spectroscopy and electrochemical detection of NO was used to determine the overall equilibrium constant $K_{NO}$ as (9.1 $\pm$ 1.2) × $10^{7}$ $M^{-1}$ at 25 $^{o}\textrm{C}$ and pH = 5.0. Stopped-flow kinetic studies on the reaction of acetate-buffered solutions of $[Ru^{III}(edta)H_{2}O]^{-}$ with NO gave $k_{on}$ values two orders of magnitude lower than that reported in the literature as a result of buffer effects. The values of $k_{on}$ determined at low and high pH, viz. 3.8 × $10^{4}$ and 1.2 × $10^{5}$ $M^{-1}$ $s^{-1}$, respectively, are significantly smaller than that found at pH = 5.0, and in agreement with that observed for the substitution reactions of $Ru^{III}(edta)$ with other entering nucleophiles. Attempts to determine $k_{on}$ for the binding of NO to $[Ru^{III}(edta)H_{2}O]^{-}$ using laser flash photolysis failed due to the occurrence of side reactions. Under specific conditions (NO in excess and ${NO_{2}}^{-}$ as impurity), the formation of the disubstituted $[Ru^{II}(edta)(NO^{+})({NO_{2}}^{-})]^{2-}$ species was detected using $^{15}\textrm{N}-NMR$ spectroscopy. Laser flash photolysis of this complex leads to multiple chemical reaction steps as a result of the formation of two primary photoproducts, which decay with di fferent rate constants to the starting complex. Possible mechanisms for these photoinduced reactions are proposed and compared to related systems reported in the literature.pl
dc.affiliationWydział Chemii : Zakład Chemii Nieorganicznejpl
dc.contributor.authorWanat, Alicjapl
dc.contributor.authorSchneppensieper, Thorstenpl
dc.contributor.authorKarocki, Andrzejpl
dc.contributor.authorStochel, Grażyna - 132108 pl
dc.contributor.authorvan Eldik, Rudi - 239234 pl
dc.date.accessioned2015-09-22T10:41:25Z
dc.date.available2015-09-22T10:41:25Z
dc.date.issued2002pl
dc.description.admin[AU] van Eldik, Rudi [SAP14007947]pl
dc.description.number6pl
dc.description.physical941-950pl
dc.identifier.doi10.1039/B108236Cpl
dc.identifier.eissn1364-5447pl
dc.identifier.issn1472-7773pl
dc.identifier.urihttp://ruj.uj.edu.pl/xmlui/handle/item/15753
dc.languageengpl
dc.language.containerengpl
dc.rightsDodaję tylko opis bibliograficzny*
dc.rights.licencebez licencji
dc.rights.uri*
dc.subtypeArticlepl
dc.titleThermodynamics and kinetics of $Ru^{III}(edta)$ as an efficient scavenger for nitric oxide in aqueous solutionpl
dc.title.journalJournal of the Chemical Society. Dalton Transactionspl
dc.typeJournalArticlepl
dspace.entity.typePublication
dc.abstract.enpl
The edta complex of $Ru^{III}$ reacts very rapidly with NO in aqueous solution at pH=5 to form a stable nitrosyl complex. The results from FT-IR (ATR) and $^{15}\textrm{N}-NMR$ studies clearly support the $NO^{+}$ character of coordinated NO, such that the nitrosyl product can be formulated as $[Ru^{III}(edta)NO]^{+}$. A combination of UV-Vis spectroscopy and electrochemical detection of NO was used to determine the overall equilibrium constant $K_{NO}$ as (9.1 $\pm$ 1.2) × $10^{7}$ $M^{-1}$ at 25 $^{o}\textrm{C}$ and pH = 5.0. Stopped-flow kinetic studies on the reaction of acetate-buffered solutions of $[Ru^{III}(edta)H_{2}O]^{-}$ with NO gave $k_{on}$ values two orders of magnitude lower than that reported in the literature as a result of buffer effects. The values of $k_{on}$ determined at low and high pH, viz. 3.8 × $10^{4}$ and 1.2 × $10^{5}$ $M^{-1}$ $s^{-1}$, respectively, are significantly smaller than that found at pH = 5.0, and in agreement with that observed for the substitution reactions of $Ru^{III}(edta)$ with other entering nucleophiles. Attempts to determine $k_{on}$ for the binding of NO to $[Ru^{III}(edta)H_{2}O]^{-}$ using laser flash photolysis failed due to the occurrence of side reactions. Under specific conditions (NO in excess and ${NO_{2}}^{-}$ as impurity), the formation of the disubstituted $[Ru^{II}(edta)(NO^{+})({NO_{2}}^{-})]^{2-}$ species was detected using $^{15}\textrm{N}-NMR$ spectroscopy. Laser flash photolysis of this complex leads to multiple chemical reaction steps as a result of the formation of two primary photoproducts, which decay with di fferent rate constants to the starting complex. Possible mechanisms for these photoinduced reactions are proposed and compared to related systems reported in the literature.
dc.affiliationpl
Wydział Chemii : Zakład Chemii Nieorganicznej
dc.contributor.authorpl
Wanat, Alicja
dc.contributor.authorpl
Schneppensieper, Thorsten
dc.contributor.authorpl
Karocki, Andrzej
dc.contributor.authorpl
Stochel, Grażyna - 132108
dc.contributor.authorpl
van Eldik, Rudi - 239234
dc.date.accessioned
2015-09-22T10:41:25Z
dc.date.available
2015-09-22T10:41:25Z
dc.date.issuedpl
2002
dc.description.adminpl
[AU] van Eldik, Rudi [SAP14007947]
dc.description.numberpl
6
dc.description.physicalpl
941-950
dc.identifier.doipl
10.1039/B108236C
dc.identifier.eissnpl
1364-5447
dc.identifier.issnpl
1472-7773
dc.identifier.uri
http://ruj.uj.edu.pl/xmlui/handle/item/15753
dc.languagepl
eng
dc.language.containerpl
eng
dc.rights*
Dodaję tylko opis bibliograficzny
dc.rights.licence
bez licencji
dc.rights.uri*
dc.subtypepl
Article
dc.titlepl
Thermodynamics and kinetics of $Ru^{III}(edta)$ as an efficient scavenger for nitric oxide in aqueous solution
dc.title.journalpl
Journal of the Chemical Society. Dalton Transactions
dc.typepl
JournalArticle
dspace.entity.type
Publication
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