Photocatalytic Systems. XVI. Photo‐oxidation of Octacyano Molybdate (IV) by Excitation in the Long‐Wave Range

Rehorek, Detlef; Salvetter, Jürgen; Hantschmann, Achim; Hennig, H.

doi:10.1002/prac.19793210123

Cited by 11 publications

(3 citation statements)

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“…The generation of oxidized cyanometallates upon IPCT excitation has been detected by UV/Vis (see Figure 2 for 1 ) and ESR spectroscopy 21. Phenyl radicals, the decay product of Ph 2 I .…”

Section: Resultsmentioning

confidence: 99%

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Photoinduced Chain Reactions of Alcohols in the Presence of Diphenyliodonium Ion Pairs with Cyanometallates—Steady State UV/Visible Spectroscopic and Pulse Radiolysis Studies

et al. 2001

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Diphenyliodonium ions (Ph2I+) form donor-acceptor ion pairs with suitable cyanometallates such as [Mo(CN)8]4-, [W(CN)8]4-, [Ru(CN)6]4- and [Os(CN)6]4-. Such ion pairs are characterized by new spectroscopic transitions due to second-sphere interactions between donor ([M(CN)x]4-, x=6, 8) and acceptor (Ph2I+) ions. Photochemical excitation of these ion-pair charge-transfer (IPCT) states leads to efficient electron transfer reactions that yield short-lived diphenyliodyl radicals (Ph2I*) and oxidized cyanometallates ([M(CN)x]3-). Diphenyliodyl radicals decay to iodobenzene and phenyl radicals. This very convenient source for generating phenyl radicals was applied to the photoinduced chain oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones, respectively. However, unexpected side reactions led to undesired chain-terminating reactions. Adduct formation of diphenyliodonium ions with alpha-hydroxyalkyl radicals was verified by pulse radiolysis studies. These relatively longlived adducts give rise to chain-terminating reactions because of interactions with [M(CN)x]4- complexes that lead to oxidized cyanometallates [M(CN)x]3- upon regeneration of the starting alcohols.

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“…The generation of oxidized cyanometallates upon IPCT excitation has been detected by UV/Vis (see Figure 2 for 1 ) and ESR spectroscopy 21. Phenyl radicals, the decay product of Ph 2 I .…”

Section: Resultsmentioning

confidence: 99%

“…Phenyl radicals, the decay product of Ph 2 I . radicals, were identified by ESR spectroscopy with nitrosodurene as spin trap 21. Upon H‐abstraction in the presence of H‐donors such as primary and secondary alcohols, phenyl radicals yield benzene.…”

Section: Resultsmentioning

confidence: 99%

Photoinduced Chain Reactions of Alcohols in the Presence of Diphenyliodonium Ion Pairs with Cyanometallates—Steady State UV/Visible Spectroscopic and Pulse Radiolysis Studies

et al. 2001

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“…With regard to the metal complex a distinction between the metal and the ligand as the donor site can be made. Frequently cyano complexes were used as donors [31,[61][62][63][64][65][66] is also called paraquat 2 + or methylviologen 2 + ) was published by Curtis, Sullivan, and Meyer [63]. Besides classical cyano complexes also metal carbonyl anions such as [Co(CO)J~ [15,67] and [M(CO) 6 ]~ with M = V, Nb, and Ta [68][69][70] are suitable donors.…”

Section: Ion Pairs Consisting Of a Complex And A Non-metallic Countermentioning

confidence: 99%

Photochemistry of transition metal complexes induced by outer-sphere charge transfer excitation

Vogler

Kunkely

1990

Topics in Current Chemistry

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Untersuchungen zur Photolyse von Diaryliodoniumsalzen

Timpe

Schikowsky

1989

J. Prakt. Chem.

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Investigations on Photolysis of Diaryliodonium Salts The photolysis of diaryliodonium salts in solution leads to various competitive and consecutive reactions. Upon irradiation, the excited state desactivates mainly through homolytic cleavage of the CI‐bond, but to a minor extent also through heterolytic cleavage of the same bond. Thus, several photolysis products have been obtained: aromatics, new iodonium salts, iodoaromatics, substitution products of the solvent, protonic acid in aqueous solutions, iodide and iodate ions and iodine. In the case of diphenyliodonium iodide the yields of iodine are higher compared to those of other salts because of electron transfer processes. The quantum yields of the disappearance of the iodonium salt (ΦI) and of the formation of protonic acids (ΦP) are equal within the experimental error. These values do not depend on the nature of the solvent, with the exception of H‐donor solvents, on the initial salt concentration and on oxygen. But, they depend strongly on the light intensity and on the substituent at the aromatic ring. The ΦP‐data also depend on the oxidation potential of the anion used. For diphenyliodonium chloride, the quantum yield of iodobenzene formation reaches only the half of the values for ΦI and ΦP. A kinetic scheme is given for the explanation of the light intensity dependence, which is based on 1. and 2. order reactions of intermediates formed by the homolytic pathway. It is assumed, that the electron transfer reaction by iodide salts proceeds only between the iodide ion and the intermediate products.

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Photocatalytic Systems. XVI. Photo‐oxidation of Octacyano Molybdate (IV) by Excitation in the Long‐Wave Range

Cited by 11 publications

References 3 publications

Photoinduced Chain Reactions of Alcohols in the Presence of Diphenyliodonium Ion Pairs with Cyanometallates—Steady State UV/Visible Spectroscopic and Pulse Radiolysis Studies

Photoinduced Chain Reactions of Alcohols in the Presence of Diphenyliodonium Ion Pairs with Cyanometallates—Steady State UV/Visible Spectroscopic and Pulse Radiolysis Studies

Photochemistry of transition metal complexes induced by outer-sphere charge transfer excitation

Untersuchungen zur Photolyse von Diaryliodoniumsalzen

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