Dioxygen complexes rhodium

There are also several situations where the metal can act as both a homolytic and heterolytic catalyst. For example, vanadium complexes catalyze the epoxidation of allylic alcohols by alkyl hydroperoxides stereoselectively,57 and they involve vanadium(V) alkyl peroxides as reactive intermediates. However, vanadium(V)-alkyl peroxide complexes such as (dipic)VO(OOR)L, having no available coordination site for the complexation of alkenes to occur, react homolyti-cally.46 On the other hand, Group VIII dioxygen complexes generally oxidize alkenes homolytically under forced conditions, while some rhodium-dioxygen complexes oxidize terminal alkenes to methyl ketones at room temperature. 

As recently reported, rhodium-dioxygen complexes such as RhCl(02)(PPh3)2 can transfer both dioxygen atoms to one mole of coordinated 1,5-cyclooctadiene to give cyclooctane-1,4-dione, without the intermediate formation of monoketone (equation 61). In the presence of excess PPh3, the reaction becomes slightly catalytic.212... 

Rh02[As(CBH6)3]i +A"(A" = PFe" or ClOa"). This rhodium dioxygen complex is prepared by reaction of chloro(4,5-cyclooctadiene)rhodium(I) dimer (Strem) with triphenylarsine in the presence of oxygen (air) followed by addition of NHaPFe or LiClOa. ... 

The cyclopentadienyl group, or its substituted derivatives, might be expected to stabilize dioxygen complexes or to ultimately react with dioxygen under the influence of transition metal centers. In rare cases, other (uncharged) dienes can also be found to stabilize dioxygen complexes of rhodium. Also discussed here are some reports of metallaben-zene systems and their reactions with dioxygen. 

Generally, while S02 reacts with dioxygen complexes of iridium, the reverse reaction, in which dioxygen reacts with S02-Ir complexes, is rare (187). However, when the chelating triphos ligand, H3CC(CH2-PPh2)3, is used, as in 73, such a reaction can be observed (189) for both iridium and rhodium. 

Costa G., Tavagnacco C., Mahajan R. Electrocatalytic dioxygen reduction in the presents of cobalt and rhodium-oximes complexes. Bulletin of electrochemistry 1998 14(2) 78-85. 

Tetrafluoroborate,223 tetraphenylborate and iodide227 salts of a large range of rhodium(I) complex cations react oxidatively with dioxygen (equation 242). The physical properties of the dioxygen complexes are given in Table 80. The claim that a rhodium(I) species containing a ditertiary arsine... 

Table 80 Physical Properties of Dioxygen, Disulfur and Diselenium Rhodium(III) Complexes containing...

Pentacoordinate complexes can also arise from reactions between rhodium(I) complexes and dioxygen. The reactions between the complexes and dioxygen under very slightly different conditions can, however, easily give rise to other products. 

The formation of 7 j/ complexes has also been reported for rhodium(II) porphyrin complexes on oxygenation and the iron dioxygen complexes will also undergo inner sphere reduction to give Fe(III)OOFe(ni) ... 

The complexes of rhodium and iridium are generally less reactive than those of palladium and platinum no reaction was observed between Rh and Ir dioxygen complexes and CO2, CS2, aldehydes and ketones or between an iridium complex and CO, CO2 and The iridium complexes are not totally inert however, and reactions with... 

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