Catalysis of the Cerous–Ceric Electron Exchange Reaction by Fluoride

Hörnig, Hannelore; Libby, W. F.

doi:10.1021/j150499a011

Cited by 20 publications

(8 citation statements)

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“…(a) Catalytic effect Certain anions, particularly halide ions, catalyze electron-exchange reactions; for example, marked chloride catalysis was found in the europous-europic re-A + S = A+ + S-S-+ B [S-+ -»• S + B- action and in the ferrous-ferric system. Libby also demonstrated catalysis by fluoride ion of the cerous-ceric electron exchange (37). In several studies where detailed kinetic analyses of this effect were carried out, thermodynamically stable ion-pairs or halide complexes were identified.…”

Section: The Anion Effectmentioning

confidence: 93%

“…One manner in which the high repulsion energy of two cations can be reduced is by the introduction of an anion between them. This has been proposed by several authors (15,33,37,46,70,71). The effect of the introduction of a univalent anion c on the repulsion energy e2(paqb/rab -pa/racqb/rbc) can be shown by the following oversimplified calculation: suppose a ferrous ion is located 2 A. from a chloride ion, which in turn is located 2 A. from a ferric ion; the potential energy for the linear complex is now attractive: is certainly not accurate, but serves to indicate the tremendous change in the electrostatic repulsive energy that occurs when a suitable anion is introduced into the activated complex.…”

Section: B Anion and Solvent Effects And The Bridged Activated Complexmentioning

confidence: 97%

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Inorganic Oxidation-Reduction Reactions in Solution Electron Transfers

Zwolinski¹,

Marcus²,

Eyring³

1955

Chem. Rev.

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Section: The Anion Effectmentioning

confidence: 93%

Section: B Anion and Solvent Effects And The Bridged Activated Complexmentioning

confidence: 97%

Inorganic Oxidation-Reduction Reactions in Solution Electron Transfers

Zwolinski¹,

Marcus²,

Eyring³

1955

Chem. Rev.

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“…Cerium.-Ceric compounds were extracted from cerous compounds by the use of ether after solution in nitric acid (8).…”

Section: Methodsmentioning

confidence: 99%

A Search for the Chemical Effects of Internal Conversion Following Radiative Neutron Capture

Maddock¹,

Maine²

1956

Can. J. Chem.

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The possibility that neutron capturc would lead t o oxidation, because of internal conversion of the capture radiation, has been investigated in solid compounds of the lower valence states of antimony, arsenic, cerium, chromium, and thallium. Except in the hydrated compounds, negative results have Iheen obtained. I t is possible that oxidation is followed by electron-transfer exchange in the irradiated solids. ISTRODUCTIONWhen an atom captures a thermal neutron, there results a highly excited compound nucleus which quicldy radiates its excess energy in one or more gamma-rays. Conservation of momentum requires that the emission of these gamma-rays imparts to the newly formed atom a recoil energy many times that required for brealiing chemical bonds. I t is also possible that one or more of the gamma-rays might be internally converted and in this instance, oxidation of the atom will result. Most studies on the chemical changes following thermal neutron capture have focused on the bond brealiing mechanisms, but there could be oxidation effects due to internal conversion, even if simple ionic solids were irradiated (10).The physical detection of internal conversion following radiative neutron capture is attended with some experin~ental difficulties; but with a 180° betaray spectrograph Hibdon and R/Iuehlhause (7) have detected the conversion electroils fi-om neutron capture in .i8Cd113, 66DylG4, 64Gdodd, 88Hg11)1), and 62sm149. Therinal neutron irradiatioil of ethyl bromide and iodide a t pressures of three microns leads to 12 to 50% of the radioactive atoms of the diffei-ent isotopes becoming positively charged as a result of internal convei-sion (16). Most of the gold and iridium recoil atoms which escape froin the surface of gold and iridium films during neutron irradiation are positively charged (12, 19).I t seemed possible that chemical methods might provide a more sensitive means of detection and estimation of the internal conversion. Radioactive perrhenate has been separated after dissolution of neutron-irradiated rhenium trichloride (6). Following the neutron irradiation of several hydratecl chi-omic salts, 3 to 10% of the radioactive chromium atoms were found in the hexavalent state upon solutioil and analysis of the crystals (4). EXPERIMENTALIn the present work, neutron irradiation of several simple inorganic salts with the cation in the lower of its two stable chemical valeilces was followed by dissolution of the solids in solutions coiltainillg as carriers cations of both valence states. There followed a chemical separatioil of the cations by a method l~llalzirscript received December 12, 1965

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“…In all of the stud ies, influence on the rate by anions was observed. Hornig & Libby (246) studied the catalysis by fluoride of the Ce+++ -Ce(IV) exchange. By study ing the effect of Cr++ on the Cr(H20) o+++-H20 exchange, Plane & Taube (180) showed the electron exchange Cr++ -Cr(H20)s+++ to proceed at a con· veniently slow rate, and to be subject to catalysis by Cl-.…”

Section: Ij2dbi'2'mentioning

confidence: 99%