Mixed iron complexes

Mixed arene-2,5-dihydro-l,2,5-thiadiborole-iron complexes have been synthesized by a novel route thermally unstable bis(arene)iron sandwich complexes, prepared by cocondensation of iron atoms with arene, react in the temperature range of -100 to -60°C with free Et2C2B2Mc2S to form reactive intermediates that decom-... 

In summary, the fragmentary evidence at hand suggests that sulfur was the primordial iron complexing material and that this ligand system was selectively modified by stepwise transition to a mixed sulfur-nitrogen and sulfur-oxygen and, finally, to an all-oxygen type of coordination. 

A number of binuclear iron complexes have also been isolated (with a neutral base attached to each metal in an axial position). The iron complexes undergo net two-electron redox reactions with dioxygen to yield products containing two identical low-spin Fe(n) metal sites superoxide or peroxide are simultaneously generated. Remarkably, the reaction can be partially reversed by removal of 02 from the system by, for example, flushing with N2 in a mixed aqueous solvent at 0°C. 

We found that LiHBEt3 cleanly reduces the ethylvinyl ether salt 18b in THF to a 6-ethoxyethyl iron complex in 80% yield In contrast, Pt PMe+BHi - in CH2C12 transforms 18b into 1 1 mix-... 

Electronic and vibrational spectroscopy continues to be important in the characterization of iron complexes of all descriptions. Charge-transfer spectra, particularly of solvatochromic ternary diimine-cyanide complexes, can be useful indicators of solvation, while IR and Raman spectra of certain mixed valence complexes have contributed to the investigation of intramolecular electron transfer. Assignments of metal-ligand vibrations in the far IR for the complexes [Fe(8)3] " " were established by means of Fe/ Fe isotopic substitution. " A review of pressure effects on electronic spectra of coordination complexes includes much information about apparatus and methods and about theoretical aspects, though rather little about specific iron complexes. ... 

Electric fleld gradient, 22 214-218 Electroabsorption spectroscopy, 41 279 class II mixed-valence complexes, 41 289, 291, 294-297 [j(jl-pyz)]=+, 41 294, 296 Electrocatalytic reduction, nickel(n) macro-cyclic complexes, 44 119-121 Electrochemical interconversions, heteronuclear gold cluster compounds, 39 338-339 Electrochemical oxidation, of iron triazenide complexes, 30 21 Electrochemical properties fullerene adducts, 44 19-21, 33-34 nickeljll) macrocyclic complexes, 44 112-113... 

FIA was used to optimise sampling from a tablet dissolution apparatus in order to determine the rate of release of iron (II) from a sustained release formulation. The dissolution medium was automatically sampled at 30-minute intervals and the 100/rl aliquots of medium were mixed with the iron complexing agent ferrozine, diluted and then passed into a spectrophotometric detector. The system was microprocessor controlled thus enabling unattended sampling of the dissolution medium for a prolonged period."... 

The reaction of hexacyanometalates with metal complexes chelated by penta-dentate ligands may afford polynuclear complexes. The presence of the penta-dentate ligand precludes the polymerization that leads to extended systems. The preparation of a representative heptanuclear, mixed-valance iron complex, [Fe (CNFe° (salmeten))6]Cl2 6H20, is detailed herein. 

We recently studied the ESR spectra of the mixed heme complex 24, where the nitrogen monoxide radical is inserted into the sixth coordinate site of heme-iron as a probe28 in order to examine the electronic structure of the heme complex29. Figure 6(a) shows the ESR spectrum of the NO radical which coordinates to the imidazole-ferriheme complex. The hyperfine stmcture (hfs) due to the N of the... 

The rate of the spin state change for the octahedral cobalt(II) complexes is expected to be faster than that observed for the iron(II) and iron(III) complexes. In the cobalt(II) case the spin state change involves only one electron, that is AS = 1. The 2E and 4T states are directly mixed by spin-orbit coupling (10, 163). The spin state transition should be adiabatic, with k = 1, without any spin-forbidden barrier. Furthermore, the coordination sphere reorganization involves a change in bond length of 21 pm along only two bonds, instead of all six bonds as in iron complexes. Both of these factors lead to the prediction of rapid spin state interconversion. 

The organometallic chemistry of the first-row transition metals generally starts with the binary metal carbonyl organometallic complexes. Noncarbonyl organometallic complexes starting with other easily accessible binary compounds provide entries to a broader spectrum of complexes. In this context, we describe the synthesis of the mixed sandwich complex (tj5-pentamethylcyclopentadienyl) ( j5-cyclopentadienyl) iron as an example of the synthetic utility of the solution-stable derivative (>j5-pentamethyl-cyclopentadienyl) (2,4-pentanedionate) iron. 

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