Chemical and electrochemical reduction

The aqueous solution chemistry of Ir in its higher oxidation states III, IV, and V has been explored by Sykes et al.41,48 Chemical and electrochemical oxidation of Ir(H20)6]3+ gives a brown-green Irv product, which undergoes chemical and electrochemical reduction to a blue and a purple IrIV complex. 170 NMR studies are consistent with double- and single-bridged dimeric structures, with likely formulas [(H20)4Ir(/i-0H)2Ir(H20)4]6+ for the blue complex and [(H20)5Ir(/r-0)Ir(H20)5]6+ for the purple one. 

Tinnemans et al.132 have examined the photo(electro)chemical and electrochemical reduction of C02 using some tetraazamacrocyclic Co(II) and Ni(II) complexes as catalysts. CO and H2 were the products. Pearce and Pletcher133 have investigated the mechanism of the reduction of C02 in acetonitrile-water mixtures by using square planar complexes of nickel and cobalt with macrocyclic ligands in solution as catalysts. CO was the reduction product with no significant amounts of either formic or oxalic acids... 

T. Yamamoto, K. Sugiyama, T. Kushida, T. Inoue, and T. Kanbara, Preparation of new electron-accepting Tr-conjugated polyquinoxalines. Chemical and electrochemical reduction, electrically conducting properties, and use in light-emitting diodes, J. Am. Chem. Soc., 118 3930-3937, 1996. 

ET-induced cycloadditions of polycyclic olefins and cycloreversions of cyclobutane species have been studied by ESR spectroscopy [266]. Upon chemical and electrochemical reduction, 2,2 -distyrylbiphenyl rearranges by intramolecular coupling into a bis-benzylic dihydrophenanthrene dianion (Scheme 1), which can be either protonated to a 9,10 -dibenzyl-9,10-dihydrophenanthrene or oxidatively coupled to a cyclobutane species. It is interesting to note that the intramolecular bond... 

Understandably, most workers who use radiolysis, photoionization, CTFS, or CTTS as the means for generation of (secondary) radical ions pay little attention to the nature of short-lived precursors of these ions. After all, the subject of interest is a secondary rather than a primary ion. This ad hoc approach is justifiable because radiolytic production is just another means of obtaining a sufficient yield of the radical ion. Quite often in such studies, the radiolysis is complemented by other techniques for radical ion generation, such as plasma oxidation, electron bombardment-matrix deposition, and chemical and electrochemical reduction or oxidation. While the data obtained in these studies are useful, there is little radiation chemistry in such—nominally, radiation chemistry—studies. 

Tinnemans, A.H.A., Koster, T.P.M., Thewissen, D.H.M.W. and Mackor A. 1984. Tetraaza-macrocyclic cobalt(II) and nickel(II) complexes as electrontransfer agents in the photo( electro )chemical and electrochemical reduction of carbon dioxide. Recl.Trav.Chim. Pavs-Bas 103. 288-295. 

The redox chemistry of pyrazines has long been of interest to organic chemists. The chemical and electrochemical reduction of compounds (44) and (45) are reported in a comparative study. 

Table 1 Chemical and Electrochemical Reductions or Oxidations in Organic Chemistry... 

Scheme 16.1 Chemical and electrochemical reduction of l,3-bis(2,4,6-trimethylphenyl)imida-zoUum cation (Reprinted from Ref [55] with kind permission of The Royed Society of Chemistry)...

For example, it is possible to find with the help of the STM images that the highly crystalline nature of the oxide film on the nickel surfaces is Ni(100) in the alkaline solutions [46]. At low potentials, a well-ordered rhombic structure is formed, which is resistant to reduction and is assigned to the irreversible Ni(OH)2 formation. At higher potentials, it is possible to see a quasi-hexagonal structure consistent with NiO(lll). In other words, a crystalline oxide is formed of the NiO(lll) order independently of the crystal orientation of nickel. Moreover, it is very useful and practical to obtain a reduced surface by the cathodic treatments, where the hydrogen evolution produces the chemical and electrochemical reductions of nickel. However, this has to be done with careful attention and in light alkaline solutions to avoid nickel dissolution. When this is performed, monoatomic steps mostly oriented in the (100) and (111) directions are observed [47]. 

Abdel-Hamid and co-workers (91BCJ3713, 91BSF884) (Scheme 198) studied the kinetics of the chemical and electrochemical reduction of 4-(arylmethylene)-pyrazol-3-ones 676a,b and 4,4-dimethylpyrazol-3-one 681. The study was conducted in... 

Zhuang GV, Xu K, Yang H, low TR, Ross PN (2005) Lithium ethylene dicarbonate identified as the primary product of chemical and electrochemical reduction of EC in 1.2 M LiPFgEC EMC electrolyte. J Phys Chem B 109 17567-17573... 

Metal nanostructures Chemical and electrochemical reduction of metal salts in solution and at liquidlliquid interface [67- 74, 84] Electrochemical synthesis from sacrificial anode [59, 95, 96]... 

EPR and ENDOR spectra of the semiquinones from a series of hypocrellin derivatives have been obtained following chemical and electrochemical reduction. ... 

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