Iron complex dinuclear

A photoinduced synthesis of the silylene-bridged dinuclear iron complex 71 has been accomplished from CpFe(CO)2SiMe3 and RSiH3. 

In the same year, Evans and coworkers reported the electrochemical reduction of protons to H2 catalyzed by the sulfur-bridged dinuclear iron complex 25 as a hydrogenase mimic in which acetic acid was used as a proton source [201]. The proposed mechanism for this reaction is shown in Scheme 60. The reduction of 25 readily affords 25 via a one electron reduction product 25. Protonation... 

In addition to tri- [105] and tetradentate N-ligands, mononuclear and dinuclear iron complexes with pentadentate N,N,N,N,0-ligands were applied to alkane... 

For analogous transformations on dinuclear iron complexes, see E. H. Braye and W. Hubei, Chem. Ind. (London), 1250 (1959). 

Jensen KB (1996) Mono and Dinuclear Iron Complexes. PhD Thesis, University of Southern Denmark, Odense... 

DNICs are spontaneously [128] formed in aqueous media using a simple Fe(II) salt, S-nitrosothiol and thiol, with a ratio of Fe2+/RSH of 1 20. NO is transferred quantitatively from the sulfur atom in the RSNO to the iron. The complete mechanism is yet to be fully determined. A 1 2 ratio results in the formation of an EPR silent yellow dinuclear iron complex ([Fe2(RS)2(NO)4]. At the higherer ratio, the green paramagnetic, mononuclear dinitrosyl predominates. The reaction is very straightforward at pH 7.8, under an inert atmosphere and in water. Under anaerobic conditions the stability of this compound is enhanced, however, in the presence of air and hydrogen peroxide, it readily decomposes to give the dinuclear complex [126] which is similar in structure to the Roussin red salt, as shown in Scheme 5.5. 

Certain dinuclear iron complexes are found to be efficient catalysts for the oxidation of primary and secondary alcohols with hydrogen peroxide.214 Metalloporphyrins are used as peroxidase mimics in the oxidation of phenol with hydrogen peroxide. 

The nature of other ligands in this dinuclear complex can be deduced from other spectroscopic data. It is clear that the tyrosyl radical is NOT a ligand. Reduction of the tyrosyl radical with hydroxyurea does not alter the features of the Mdssbauer (26) and EXAFS (40) data. Indeed, the only hint that the radical is in the vicinity of the dinuclear iron unit is the temperature dependence of the EPR relaxation properties of the radical signal. At liquid helium temperatures, the tyrosyl radical behaves like an isolated organic radical. But, at temperatures where the dinuclear iron complex becomes paramagnetic, the radical signal becomes harder to saturate relative to an isolated radical (114). Based on these effects, the radical is estimated to be within 10 A of the diferric site. 

X-ray structures of wild-type N. gonorrhoeae Fbp " and mutant forms of H. influenzae Fbp have been described in which multinuclear oxo-metal clusters are bound to the protein. These surprising results are informative about aspects of the Fbp structure and formation of oxo-metal clusters on a protein surface, but it is not clear whether they have any physiological relevance. Sadler and coworkers present a case for this, noting that the outer membrane transport protein FecA passes diferric dicitrate into the periplasm and so at least one dinuclear iron complex is available to Fbp. 

The use of Me3NO to induce substitution of dppm (bis(diphenylphosphino)-methane) for CO molecules on dinuclear iron complexes led to insertion of CO into C-C bonds of alkyne-derived metallacycles. Similar behavior was observed when [PPNJCl salts were used to favor the formation of alkyne-substituted triruthenium dppm-containing clusters.I This behavior should be compared with the insertion of CO into allenylidene and phosphido-bridging ligands occurring when dppm coordinates to binuclear ruthenium complexes as shown in Fig. 3. This reaction is a nucleophilic attack of the coordinated allenylidene and phosphido groups on a coordinated CO (see Section 2.8.2.2). 

Dinuclear iron complex 489 was treated with excess carbon disulfide to give complexes 490 and 491 in 66% and 71% yield, respectively (Scheme 94). 490 was characterized by X-ray crystallography. The mechanistic proposal of the authors includes a disproportionation step. ... 

A large number of dinuclear iron complexes that display catalytic activity in the hydroxylation of alkanes has been reported. These complexes actually mimic MMO in a functional manner. However, there are only a few iron complexes that display both the catalytic and the structural features of MMO and in this section we will include only these model compounds. Representative results of alkane functionalization catalyzed by dinuclear iron complexes using H2O2 as oxidant are shown in Table IV. 

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