Oxidation of Some Transition-Metal Cyanide Compounds by Hydroxyl Radical

Abstract

The oxidation of some transition-metal cyanide compounds by hydroxyl radical in aqueous media has been investigated by pulse radiolysis. For compounds of the type, M(CN)64-where M is Fe, Ru, and Os, and for Mo(CN)s4-, the mechanism of their reaction with hydroxyl radical involves single electron transfer with the formationofthe intensely colored metalcomplexes of the same stoichiometry as the startingmaterials. The u.v.-visible absorption spectra for these products for the iron, ruthenium, and osmium systems are reported along with the associated second order rate constants for their formation. The reaction of Mo(CN)s4-with hydroxyl radical has been studied by a competition technique using sodium bicarbonate. The values of the second order rate constants are near those expected of diffusion-controlled reactions and they range between cn. 5 x lo9 to I x 101° M-I s-l. Can.

A pulse radiolysis investigation of the reactions of bromine dioxide radical (BrO2.cntdot.) with hexacyanoferrate(II), manganese(II), phenoxide ion, and phenol

“…The are experimental data and the solid line is a simulation based upon the reactions in absorption spectra of the various species involved are well-known and well separated, and the radiation chemistry of Fe(CN)e4" and Fe(CN)g3" is well understood. 18 Ferrocyanide ion has no absorption spectrum above 400 nm. The featureless absorption spectra of Fe(CN)e4" and Br02• are centered upon 420 and 480 nm, respectively, and there is little overlap at these wavelengths.…”

“…More than half of the HO• adds to PhOH according to reaction 18. The product of PhOH + HO• -Ph(HO)2- (18) this addition, dihydroxycyclohexadienyl radical (Ph- for reactions 18-20 listed in Table I were determined by us in N20-saturated solutions containing only PhOH. These rate constants generally agree with those of Land Ebert32 and were used in simulations of experiments in-volving both Br03" and PhOH.…”

“…The reaction of Br02• with PhOH was included because of its proposed involvement in a mechanism15,16 of a recently discovered class of uncatalyzed, bromate-driven oscillators.17 Ferrocyanide ion (Fe(CN)64") was included as a test of the method as the radiation chemistry of Fe(CN)g4' and Fe(CN)g3' is well understood. 18 Phenoxide ion (PhO") was included as part of the work on PhOH.…”

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

“…This aspect suggests that the attack of OH • and e aq − on the complex, disturbed the conjugation of the system, but did not destroy it completely. "tptz" is an organic ligand which does not allow any direct charge transfer from the central atom to the ligand as in cyanide complexes [19,20], but a partial charge transfer leading to the formation of an adduct can take place. Hence, the reaction between Fe(tptz) 2 2+ and OH • can be represented as,…”

Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 19. Preparation and Characterization of Films of Quaternized Poly(4‐vinylpyridine)‐silica

“…) [29]. This ion pairing explains why the minimum absorbance never goes below about 50% of the maximum absorbance value for ferricyanide.…”