Iron molecular

Fig. 4.3 Ranges of isomer shifts observed for Fe compounds relative to metallic iron at room temperature (adapted from [24] and complemented with recent data). The high values above 1.4-2 mm s were obtained from Co emission experiments with insulators like NaCl, MgO or Ti02 [25-28], which yielded complex multi-component spectra. However, the assignment of subspectra for Fe(I) to Fe(III) in different spin states has never been confirmed by applied-field measurements, or other means. More recent examples of structurally characterized molecular Fe (I)-diketiminate and tris(phosphino)borate complexes with three-coordinate iron show values around 0.45-0.57 mm s [29-31]. The usual low-spin state for Fe(IV) with 3d configuration is 5 = 1 for quasi-octahedral or tetrahedral coordination. The low-low-spin state with S = 0 is found for distorted trigonal-prismatic sites with three strong ligands [30, 32]. Occurs only in ferrates. There is only one example of a molecular iron(VI) complex it is six-coordinate and has spin S = 0 [33]...

Bacterial ferredoxins. Bacterial ferredoxin was first described in 1962 by Mortenson et al. (p who found a low-molecular iron protein involved in electron transfer of pyruvate hydrogenase and nitrogenase in C. pasteurianum. Subsequently, a number of ferredoxins have been found lii widely different types of bacteria such as photosynthetic bacteria and N2-fixing bacteria. These bacterial type ferredoxins have molecular... 

Putidaredoxin. Cushman et al. (36) isolated a low molecular iron-sulfur protein from camphor-grown Pseudomonas putida. This protein, putidaredoxin, is similar to the plant type ferredoxins with two irons attached to two acid-labile sulfur atoms (37). It has a molecular weight of 12,000 and shows absorption maxima at 327, 425 and 455 nm. Putidaredoxin functions as an electron transfer component of a methylene hydroxylase system involved in camphor hydroxylation by P. putida. This enzyme system consists of putidaredoxin, flavoprotein and cytochrome P.cQ (38). The electron transport from flavoprotein to cytochrome P.cq is Smilar to that of the mammalian mixed-function oxidase, but requires NADH as a primary electron donor as shown in Fig. 4. In this bacterial mixed-function oxidase system, reduced putidaredoxin donates an electron to substrate-bound cytochrome P. g, and the reduced cytochrome P. g binds to molecular oxygen. One oxygen atom is then used for substrate oxidation, and the other one is reduced to water (39, 40). 

Rodriguez MM, Bill E, Brennessel WW, Holland PL. N(2) reduction and hydrogenation to ammonia by a molecular iron-potassium complex. Science. 2011 334 780-3. 

They formally contain Fe(IV) and Fe(V) centers and represent examples of discrete high-oxidation state molecular iron complexes. Short Fe—S ( 218 pm) and Fe—N ( 184 pm) distances indicate that in both complexes n donation from thiolate and amide donors is effective in reducing the electron deficiency at the Fe centers and stabilizing their high-oxidation states. 

Ultrashort nonbonded contacts with molecular iron in hetero- and heteraphanes 04EJO3763. 

Pascal, R. A., Molecular iron maidens Ultrashort nonbonded contacts in cyclophanes and other crowded molecules , Eur. J. Org. Chem. 2004, 3763-3771. 

PhBP 3)Fe 2(p-N)] (202), respectively, are not derived from N2 cleavage, but they represent the only examples of molecular iron nitridos known so far, that react with Fl2 (Scheme 53). Under mild conditions (ambient temperature, H2 (1 atm)) is heterolyticaUy cleaved to form... 

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