Iridium oxidation

Iridium Oxide. Iridium dioxide [12030 9-8] coatings, typically used in combination with valve metal oxides, are quite similar in stmcture to those of mthenium dioxide coatings. X-ray diffraction shows the mtile crystal stmcture of the iridium dioxide scanning electron micrographs show the micro-cracked surface typical of these thermally prepared oxide coatings. 

Abstract The purpose of this chapter is to present a survey of the organometallic chemistry and catalysis of rhodium and iridium related to the oxidation of organic substrates that has been developed over the last 5 years, placing special emphasis on reactions or processes involving environmentally friendly oxidants. Iridium-based catalysts appear to be promising candidates for the oxidation of alcohols to aldehydes/ketones as products or as intermediates for heterocyclic compounds or domino reactions. Rhodium complexes seem to be more appropriate for the oxygenation of alkenes. In addition to catalytic allylic and benzylic oxidation of alkenes, recent advances in vinylic oxygenations have been focused on stoichiometric reactions. This review offers an overview of these reactions... 

Iridium Oxide, Iridium dioxide comings, typically used in combination with valve metal oxides, arc quite similar in structure to those of ruthenium dioxide comings. 

Although the conversion of light energy to chemical energy via the electron transfer reactivity of [Ir(u pz)(COD)]2 is rather facile, the photochemical products rapidly return to starting materials because the back electron transfer reactions are highly exothermic. For example, back electron transfer between the oxidized iridium... 

NO, Nitrogen oxide, iridium complex, 21 104 NO2SC3H7, L-Cysteine, gold complex, 21 31 NO3C3H7, Serine, copper complex, 21 115 NFPtSe2C24H28, Platinum(II), (A. /V-diethyldi-selenocarbamato)methyl(triphenylphos-phine)-, 21 10... 

Yao et al. [100] reported a pH electrode based on hthium carbonate melt-oxidized iridium oxide film with the composition of Li lrOy 11H2O. The electrode based on this oxide film exhibits promising pH sensing performance and high chemical stability, with an ideal Nemstian response 58.9mV/pH over the pH range of 1 to 13. The electrode also shows a fast potential response with a 90% response time less than 0.2 s, and a low open-circnit potential drift O.lmV/day measnred in pH 6.6 solntion. The reproducibility in terms of the Nemst slopes and the apparent standard electrode potentials has been improved among electrodes within the same batch. However, the biocompatibility due to inclusion of lithium salt was not assessed. 

Homogeneous Oxidation.—Iridium(i) complexes catalyse the homogeneous oxidation of styrene and of triphenylphosphine. For oxidation of the latter the mechanism suggested is co-ordination of an oxygen molecule to give (35) intramolecular transfer of the two oxygen atoms then gives two molecules of triphenylphosphine oxide. ... 

The choice of a suitable counter-electrode for a successful EW is not easy since only a few compounds fulfil the desired operational requirements which call for an uncommon combination of electrochemical and optical properties. The most promising, and, thus far, the mostly used materials are indium tin oxide, nickel oxide, iridium oxide and cobalt oxide among the inorganic ECMs, and polyaniline (PANI) among the organic ECMs. The electrochromic properties of indium tin oxide and PANI have been described in Chapter 7. Therefore, here attention will be mainly focused on transition metal oxide counter-electrodes. 

In the H NMR, the ring protons in 9a,b are shifted even further downfield than in compounds 5—8 (Table 2). In 9a, for example, protons H1/H5 resonate at dl3.95 and H3 resonates at 67.86, as compared to (310.91 and 7.18 in compound 5. Similar downfield shifts are observed for C1/C5 and C3 in the C NMR spectrum. This downfield shifting probably reflects the inductive effect of an oxidized iridium center and two electronegative iodine atoms in the ring plane. The shifts are similar to those in the osmabenzene family, which are likewise d octahedral complexes (vide supra). 

Bowden, E.F., Hawkridge, F.M. and Blount, H.N.(1984) "Interfacial Electrochemistry of Cytochrome c at Tin Oxide, Iridium Oxide, Gold and Platinum Electrodes" J. Electroanal. Chem., 161, 355-76. 

Blouin M, Guay D (1997) Activation of rutheniiun oxide, iridium oxide, and mixed Ru[sub x]Ir[sub l x] oxide electrodes during cathodic polarization and hydrogen evoluti[Pg.1819]

Ultrafine metal fiber matrix of titanium dioxide deposited electrochemicaHy acts as double-layer electrode with wide specific surface area. Next, a metal oxide such as ruthenium oxide, rubidium oxide, iridium oxide, nickel oxide, cobalt oxide, manganese oxide, or vanadium oxide can be deposited onto substrate by electrodeposition. 

Nickel-based positive electrode made of 3 to 95 wt% NiOH balance consists of either nickel powder, cobalt powder, or carbon powder, possibly in combination. Carbon-based negative electrode made of 10 to 95 wt% carbon, with balance consisting of at least one metal oxide from group of bismuth oxide, iridium oxide, cobalt oxide, iron oxide, and iron hydroxide, and hydride from Groups IIIA, IIIB, IVA, IVB, VB, VIB, VIIB,andVIIIB. 

Mozota J, Conway BE (1983) Surface and bulk processes at oxidized iridium electrodes-1 monolayer stage and transition to reversible multilayer oxide film behavior. Electrochimica Acta 28 1-8... 

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