Radiolytic study of the reactions of hydroxyl radical with cobalt(III), iron(II), and ruthenium(II) complexes containing 2,2'-bipyridyl and cyano ligands

Maliyackel, A. C.; Waltz, William L.; Lilie, J.; Woods, Robert J.

doi:10.1021/ic00327a037

Cited by 27 publications

(16 citation statements)

References 5 publications

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“…Moreover, the spectra do not exhibit any red shift, which indicates that the nitrogen atoms are still complexed to the metal center. All these results are consistent with our previous results [9] obtained for Fe(terpy) 2 2+ , and also with those reported in literature for complexes of bipy [14][15][16] and phen [17]. In case of Fe(tptz) 2 2+ , a decrease in apparent molar extinction coefficient was observed at the characteristic peak, 596 nm.…”

Section: Resultssupporting

confidence: 93%

Reactions of 2,4,6-tripyridyl-1,3,5-s-triazine and its Fe(ii) complex with OH· and eaq-

Hela

Reddy

Anipindi

et al. 2005

React Kinet Catal Lett

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Pulse radiolysis studies indicated that OH • and e aq − formed adducts with 2,4,6tripyridyl-1,3,5-s-triazine (tptz). The OH-adduct showed an absorption maximum at 290 nm, while the adduct formed from the attack of e aq − and subsequent protonation of the anion, has an absorption maximum at 300 nm. In case of the complex, Fe(tptz) 2 2+ , both OH • and e aq − gave ligand centered adducts. All the adducts decayed by second order dimerization or disproportionation, a disproportionation reaction in case of the complex.

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Section: Resultssupporting

confidence: 93%

Reactions of 2,4,6-tripyridyl-1,3,5-s-triazine and its Fe(ii) complex with OH· and eaq-

Hela

Reddy

Anipindi

et al. 2005

React Kinet Catal Lett

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“…Ferricyanide is absent in both soluble and insoluble recovered solids. This absence was unexpected because of the known reaction of ferrocyanide with hydroxyl radical, which is formed in the gamma field, to produce ferricyanide (Maliyackel et al 1990). This oxidation may be suppressed by the presence of nitrite anion, which also reacts with hydroxyl radical.…”

Section: 18mentioning

confidence: 99%

Ferrocyanide Safety Project: Subtask 3.4, Aging Studies. FY 1992, annual report

Lilga¹,

Lumetta²,

Riemath³

et al. 1992

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"_i_eHanford Ferrocyanide Task Team is addressing issues involving ferrocyanide precipitates in single-shell waste storage tanks (SSTs), in particular the storage of waste in a safe manner. This Task Team, composed of researchers from Westinghouse Hanford Company (WHC), Pacific Northwest Laboratory (PNL), and outside consultants, was formed in response to the need for an updated analysis of safety questions about the Hanford ferrocyanide tanks. " The Ferrocyanide Safety Project at PNL is part of the Waste 'Tank Safety Program led by WHC. The overall purpose of the WHC program, sponsored by the U.S. Department of Energy's Tank. Farm Project Office, is to 1) maintain the ferroeyanide tanks with minimal risk of an accident, 2) select one or more strategies to assure safe storage, 3) close out the unreviewed safety question (USQ), and 4) identify ultimate disposal options to be used when waste is removed from the tanks. This annual report gives the resu!t_ of the work conducted by PNL in FY 1992 on Subtask 3.4, Aging Studies, which is part of Task 3, Chemical Nature of Ferrocyanide in Wastes. Subtask 3.4 deals with the aging behavior and solubilization of ferrocyanide tank waste sludges in a basic aqueous environment. Investigated were the effects of pH variation, ionic strength, salts present in SSTs, and gamma radiation on solubilization of vendor-prepared Na_NiFe(CN)6. Vendor-prepared Na_NiFe(CN)6 dissolves in aqueous base to give primarily insoluble Ni(OH)2 and soluble Na4Fe(CN)6. Precipitation of Ni(OH)2 apparently drives the ferrocyanide dissolution. From the gamma pit experiments, the in_,_uble solids contained more than one iron cyanide species, yet to be identified. The rate of dissolution of Na2NiFe(CN)6 in aqueous base increases with increasing pH. At pH 14, 95% dissolution is observed after 0.5 h. Addition of 1 M Na + ions in the form of Na2SO4 suppresses dissolution at pH 13, presumably because of a common ion effect. However, 1 M Na + in the form of SST simulant salts (sodium salts of phosphate, carbonate, nitrate, nitrite, sulfate, and hydroxide) resulted in an enhancement of the rate of solubilization most likely arising from buffering of the solution by phosphate. Even when the solution is not stirred, dissolution is relatively rapid. Approximately 40% of the Na_NiFe(CN)6 dissolves in 24 h in an unstirred solution containing SST salts. Gamma radiation does not appear to greatly affect the dissolution reaction. Similar rates were observed in unstirred irradiated and control solutions. A more complex mixture of iron cyanides in the insoluble fraction of the gamma radiation experiments is obtained, suggesting the possibility that an iron cyanide species re-precipitates from solution. Further work is needed to determine the identity of this species. Solubilization work will continue next fiscal year. In addition, cyanide and ferrocyanide hydrolysis studies will be conducted.

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“…(13)] andc an be generatedb yp rotonation of e aq À under acidic conditions, is formally as trongr eductant (E8(H + /HC) = À2.31 Vv s. NHE), it is doubtful that it ever actually reacts through outer-sphere electront ransfer.R ather,i ti sm ore common for HC to add to unsaturated bonds or metal centers, or to react with added scavengers such as formate or alcohols [Eqs. (15) and (16)]. I ti sc lear from the above discussion that the radiolysis of water permits the generation of ar ange of powerful one-electron reducing agents, some of which have been appliedf or mechanistic investigations of reductive halfreactions relevant to AP catalysis.…”

Section: Introductionmentioning

confidence: 99%

“…For example, formate is commonlyu sed for this purpose to produce the powerful reductant, CO 2 C À [Eq. (15)], which has as tandard reduction potential, E8(CO 2 /CO 2 C À ), of À1.90 Vv ersus NHE. An alternative method for the generation of CO 2 C À is the directr eduction of dissolved CO 2 by e aq À in CO 2saturated water containing tBuOH.…”

Section: Introductionmentioning

confidence: 99%

Application of Pulse Radiolysis to Mechanistic Investigations of Catalysis Relevant to Artificial Photosynthesis

2017

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Taking inspiration from natural photosystems, the goal of artificial photosynthesis is to harness solar energy to convert abundant materials, such as CO2 and H2O, into solar fuels. Catalysts are required to ensure that the necessary redox half‐reactions proceed in the most energy‐efficient manner. It is therefore critical to gain a detailed mechanistic understanding of these catalytic reactions to develop new and improved catalysts. Many of the key catalytic intermediates are short‐lived transient species, requiring time‐resolved spectroscopic techniques for their observation. The two main methods for rapidly generating such species on the sub‐microsecond timescale are laser flash photolysis and pulse radiolysis. These methods complement one another, and both provide important spectroscopic and kinetic information. However, pulse radiolysis proves to be superior in systems with significant spectroscopic overlap between the photosensitizer and other species present during the reaction. Herein, the pulse radiolysis technique and how it has been applied to mechanistic investigations of halfreactions relevant to artificial photosynthesis are reviewed.

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Radiolytic study of the reactions of hydroxyl radical with cobalt(III), iron(II), and ruthenium(II) complexes containing 2,2'-bipyridyl and cyano ligands

Cited by 27 publications

References 5 publications

Reactions of 2,4,6-tripyridyl-1,3,5-s-triazine and its Fe(ii) complex with OH· and eaq-

Reactions of 2,4,6-tripyridyl-1,3,5-s-triazine and its Fe(ii) complex with OH· and eaq-

Ferrocyanide Safety Project: Subtask 3.4, Aging Studies. FY 1992, annual report

Application of Pulse Radiolysis to Mechanistic Investigations of Catalysis Relevant to Artificial Photosynthesis

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