Oxalate radical

Oxalate radicals were detected in flash photolysis of Fe(C204)33, and in Co(C204)33 " photolysis it has been shown that scavengers such as Oa can reduce the quantum yield for reduction.63 The quantum yield observed for Co(II) production will be twice the yield of the primary... 

Co(NH3)5H20+8 are produced (81). The formation of an intermediate of the type Co(NH3)5(C204)+2 would result in the fast reduction of the Co(III) (81). If this oxidation proceeds by two fast, consecutive steps, it is hard to decide between a Co(IV) as central atom of the short lived intermediate and a partially oxidized oxalate radical ligated to Co (111). An analogous behavior has been observed in the oxidation of />-aldehydobenzoate ligated to cobalt, by double electron transfer reactants (40). 

A similar but, perhaps, more interesting case is that of the ion pairs between Co(sep)3+ and oxalate ions. Excitation of the ion pair in the IPCT band leads to the formation of the Co(II) complex and of an oxalate radical which undergoes a fast decomposition reaction. Thus, the back electron transfer reaction is prevented and Co(sep)2+, which is a good reductant, can accumulate in the system. When colloidal... 

The first step is the formation of an Fe(II) complex with an oxalate radical ligand. The oxalate radical can undergo an intramolecular reduction back to oxalate or be released into the bulk solution. C204 is consumed by reacting with either Fe(III) or 02. 

Rapid formation of a (hypothetical) bidentate, mononuclear surface complex is the important first step followed by photoexcitation of this surface complex and subsequent electron transfer to Fe(III) with formation of an oxalate radical and Fe(II). The oxalate radical undergoes a rapid decarboxyla-... 

The oxidation of [Ir(ox)3]3- by cerium(IV) in aqueous acidic sulfate or perchlorate media has given [Ir(ox)3]2. That the product is indeed [Ir(ox)3]2- and not [Irm(ox)2(C207 )]2 finds support from the slow reaction observed in the presence of excess cerium(IV) free or coordinated oxalate radical anion would be expected to react rapidly with CeIv. In solution, [Ir(ox)3]2- undergoes slow pseudo-first-order reaction to yield the highly reactive intermediate [Ir I,(ox)2(C2Oi )]2. ... 

Photoreduction of oxalato-Ti complexes in aqueous oxalic acid gave oxalato-Ti" complexes which catalysed the photosensitized decomposition of oxalic acid to CO2 and CO. Hydrolysis also occurred in the initial stages of irradiation e.p.r. signals characteristic of oxalate radicals were observed. Photochemical reduction of Ti compounds in alcohol solution is characterized by phototransfer of an electron followed by removal of H from the alcohol to give RCHOH (R = H or Me) and rearrangement of the first co-ordination sphere to give different Ti complexes depending on the temperature. ... 

Firstly, the Ru(bpy)3 + is oxidized at the electrode to the Ru(bpy)3 + cation. This species is then capable of oxidizing the oxalate ( 204 ) in the diffusion layer close to the electrode surface to form an oxalate radical anion ( 204 ). This breaks down to form a highly reducing radical anion (C02 , E° = —1.9 V vs. NHE (126)) and carbon dioxide. The reducing intermediate then either reduces the Ru(bpy)3 complex back to the parent complex in an excited state, or reduces Ru(bpy)3 to form Ru(bpy)3+ that reacts with Ru(bpy)3 + to generate the excited state Ru(bpy)3 , which emits light with -620 nm. 

Formation of oxalate radical anion from oxalate dianion)... 

Decomposition of oxalate radical anion into CO2 and CO2 radical anion One-electron oxidation of oxalate radical anion to dioxetanedione which immediately decomposes to 2 CO2... 

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