Dinudear species

Subsequently, E releases ethanal to give a Pd(0) species which is reoxidized to Pd(II) by means of Cu(II), possibly via dinudear species such as F, and Cu(II) is regenerated from Cu(I) by reaction with 02 and HC1. From the kinetics of the Wacker oxidation, which are roughly expressed [4, 22] by the equation ... 

Several types of mixed donor ligand (N—O, C—O) bridge the (Cr—Cr) unit in dinudear species (Section 35.3.5.5). 

Scheme 3.5 Formation of active species in Stanley s dinudear hydroformylation catalyst [36].

The chemistry of complexes containing cationic iridium has been studied by Merola and co-workers. Among all the complexes described in the literature, they reported the complex cis,mer-(Me3P)3IrH2Cl, whose aqueous chemistry looks very rich [25]. It resulted from the oxidative addition of H2 to [Ir(cod)(PMe3)3]Cl [26], From XH and 31P NMR measurements, they showed that two different species are formed upon dissolution in water. One species is the cationic aquo complex [mer,cis-(Me3P)3IrH2(OH2)] 17 and the other one is the dinudear cation 18 (Scheme 5). 

The redox reaction now takes place within this dinudear complex with formation of reduced Co(II) and oxidized Cr(III). The latter species forms an inert chloroaqua complex, but the cobalt(lI) is labile, so the intermediate dissociates with the chlorine atom remaining with the chromium ... 

Figure 21 Dinudear Co" species with bipy ligands and with a peroxo and hydroxo bridge this compound shows interesting...

Dinucleating systems with ligands of the bipy type are also known. Provided that the dilferent units of bipy are connected in a suitable way, dinudear compounds may be obtained, as shown in (74). With certain ligands of suffident size, however, tetracoordinate mononuclear species may also be formed (Figures 22 and 23). ... 

Mariganese-containing catalases have been isolated from three species of bacteria Lactobacillus plantarum [27], Thermus ihemtophUus [28], and Thermoleophilum album [18]. X-ray crystallographic structure analysis [29] has shown that these catalases contain a dinudear manganese core. During catalysis, the dinudear manganese active site cydes between the Mn"- and Mn2"oxidation states [30]. 

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