Complexes with iron

Chiral diene—iron tricarbonyl complexes were acylated using aluminum chloride to give acylated diene—iron complexes with high enantiomeric purity (>96% ee). For example, /ra/ j -piperjdene—iron tricarbonyl reacted with acyl haUdes under Friedel-Crafts conditions to give l-acyl-l,3-pentadiene—iron tricarbonyl complex without any racemization. These complexes can be converted to a variety of enantiomericaHy pure tertiary alcohols (180). 

Subsequent carbonylation of the alkyl-iron complexes with carbon monoxide provides the desired chiral iron-acyl complexes, with essentially complete inversion of configuration at... 

This chapter treats iron complexes with Fe-H bond(s). An H ligand on a transition metal is named in two ways, hydride and hydrido. The term hydrido is recommended to be used for hydrogen coordinating to all elements by lUPAC recommendations 2005 [1], However, in this chapter, the term hydride is used because it has been widely accepted and used in many scientific reports. 

Table 2 Comparison of iron complexes with transition precious-metal catalysts for the hydrogenation of 1-hexene...

Fink and Babik reported that propylene polymerization was achieved by a bis (imino)pyridine iron complex with Ph3C[B(C6p5)]4] and ttialkylaluminium as additives [127]. Both 3-methyl-"butyl and "butyl endgroups were observed by NMR spectrum when ttiisobutylaluminium as an activator was used, whereas the only "propyl endgroup was formed in case of triethylaluminium activation. In addition, this polymerization proceeds two times faster with than without a hydrogen atmosphere, but the value decreases and the M IM value rises up. 

Iron complexes with the pentadentate ligand 3 derived from pyridyl and prolinol building blocks containing a stereogenic center were reported from the group of Klein Gebbink (Scheme 4) [34]. In alkene oxidations with hydrogen peroxide,... 

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... 

A mononuclear diastereopure high-spin Fe alkylperoxo complex with a pen-tadentate N,N,N,0,0-ligand 33 (Scheme 17) was reported by Klein Gebbink and coworkers [109, 110]. The complex is characterized by unusual seven-coordinate geometry. However, in the oxidation of ethylbenzene the iron complex with 33 and TBHP yielded with large excess of substrate only low TON s (4) and low ee (6.5%) of 1-phenylethanol. 

A typical example of a correlation diagram for Fe is given in Fig. 4.3. It summarizes the isomer shifts for a great variety of iron complexes with oxidation states (1) to (VI) in the order of the respective high-spin, intermediate-spin, and low-spin configurations. The plot of the corresponding values marked by grey, hatched and open bars demonstrates three major trends ... 

Table 5.4 Linear fit data for Fe Mossbauer isomer shift predictions using the linear equation 5 = h (p - c) + a. A collection of 21 iron complexes with varying charge, oxidation- and spin-states have been studied (taken from [11])...

Condensation of the iron complex with cyclopentanone in perchloric acid-acetic anhydride-ether medium had been attempted. The non-crystalline residue, after methanol washing and drying in air for several weeks, exploded on being disturbed. This was attributed to possible presence of a derivative of ferrocenium perchlorate, a powerful explosive and detonator. However, methyl or ethyl perchlorates alternatively may have been involved. 

As already mentioned earlier, the ruthenium complex [Ru(bdmpza) Cl(PPh3)2l (24) easily releases one of the two phosphine ligands and allows the substitution not only of a chlorido but also of a triphenylphosphine ligand for K -coordinating carboxylato or 2-oxocarboxylato ligands (58). The purpose of these studies was to find structural ruthenium models for the active site of 2-OG dependent iron enzymes, since ruthenium(II) complexes are low spin and thus suitable for NMR characterization, whereas ferrous iron complexes with NJV,0-ligands are often difficult to investigate, due to their... 

The reaction of alkoxy(aryl)carbene iron complexes with two equivalents of an isonitrile leads to the formation of azetidin-2-ylidene complexes [197]. For other reactions of Fischer-type carbene complexes with isonitriles see [198]. 

As already briefly mentioned, the oxygen-atom insertion into Si—H bonds of silanes constitutes a selective method for the chemoselective preparation of silanols, which has been much less studied compared to the CH oxidation. This unique oxyfunctionalization of silanes is also highly stereoselective (equation 35) since, like the CH insertions, it proceeds with complete retention of configuration. A novel application of the SiH insertion process is the synthesis of the unusual iron complex with a silanediol functionality, in which selectively both Si—H bonds of the silicon atom proximate to the iron ligand are oxidized in the silane substrate (equation 36). ... 

Vanin, A. F. (1967). Identification of divalent iron complexes with cysteine in biological systems by the EPR method. Biochemistry (USSR) 32, 228-232. 

Fig. 10. Water-free iron complex with dioxygen placed above the cofactor (5a) and the transition state for dioxygen coordination to iron (TS[5a-6a] ). Distances are given in angstroms.

The catalytic cycle is completed by reformation of the hexacoordinate iron complex, with the 2-His-l-Glu binding motif and three... 

Iron crosses the luminal membrane of the intestinal mucosal cell by two mechanisms active transport of ferrous iron and absorption of iron complexed with heme (Figure 33-1). The divalent metal transporter, DMT1, efficiently transports ferrous iron across the luminal membrane of the intestinal enterocyte. The rate of iron uptake is regulated by mucosal cell iron stores such that more iron is transported when stores are low. Together with iron split from absorbed heme, the newly absorbed iron can be actively transported into the blood across the basolateral membrane by a transporter known... 

The antitumor antibiotic bleomycin (BLM) is believed to cause cytotoxicity through its ability, in the combined presence of dioxygen and a metal ion cofactor (204), to bind to and degrade DNA (205). Iron complexes of BLM have aroused special attention, as such complexes are the first (vide supra concerning the discussion of hemerythrin and hemocyanin) non-heme-iron complexes with a significant capacity for dioxygen activation (206). 

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