Absorption spectra iron chlorides

Treatment of TPPFe(III)Cl or raeso-tetra-o-tolylporphinato-iron(III) chloride [TTPFe(III)Cl (10)] with iodosylbenzene caused rapid oxidation of the porphyrin and loss of catalytic activity for hydrocarbon oxidation. Figure 1 shows changes in the visible absorption spectrum upon treatment of 10 with iodosylbenzene. These data indicate that shortly after the addition of iodosylbenzene (Scan b, Figure 1) a new porphyrin species (11) is formed, which then rapidly decays to oxidized porphyrin products. The kinetics of this decay process are approximately first order (Figure 2). 

Figure 5 shows that the absorption spectrum of the tetrachloroferrate ion, with a characteristic maximum at 3150 A., is completely developed in such a solution. The dotted line is the spectrum of an oxidation mixture. The spectrum resembles that of a solution of FeC, but the characteristic maximum at 3600 A. appears to be shifted to 3580 A., and the extinction coefficient at the latter wavelength is lower than that at 3150 A. The result suggests that the principal iron (III) species in the oxidation mixtures is Cl3Fe( OCH3)". Figure 6 shows the effect of metallic chlorides on the spectrum of methanolic solutions of ferric chloride. 

Figure 3 shows the Mossbauer spectra for an alloy of 75% iron and 25% rhodium after two different heat treatments. Since absorption rather than transmission is plotted, these curves are right side up. The upper spectrum is taken from an alloy which was annealed in the low temperature field (cesium chloride structure), and there are two six-hne patterns... 

The solution is cooled in an ice bath and is stirred rapidly as 9.65 g (0.107 mole) of l-chloro-2-methyl-l-propene (isobutenyl chloride) [Aldrich] is added over a period of 5 min. The reaction can be followed by observing the changes in the IR spectrum of the solution. The carbonyl absorption bands characteristic of the anion are replaced by those typical of the product at 1998 and 1950 cm. Upon completion of the addition of l-chloro-2-methyl-l-propene, stirring at 0" is continued for 1 hr to ensure completion of the reaction. The resulting solution of dicarbonyl (Ti -cyclopentadienyl)(2-methyl-l-propenyI-KC )iron may be used directly without purification. Alternatively, the product can be isolated and purified by removing solvent under reduced pressure, followed by chromatogra(>Ay of the residue on 300 g of neutral activity III alumina. The column is made up in anhydrous diethyl ether, and after dissolving the crude product in petroleum ether, elution under N2 is carried out with this solvent. The product may 6e further purified by short-path distillation at pressures less than 10 mm (pot temperature less than 40°). It is then sufficiently pure to be stored at -20° for... 

The complexes prepared in this manner are blue or brown and are air- and moisture-sensitive. However, they can be stored for several months under N2. They are diamagnetic and soluble in most organic solvents except petroleum ether and similar hydrocarbons. In the far-IR spectrum, several absorption bands occur in the vicinity of 250-300 cm. These are assigned to V(m cd- The X-ray crystal structure of WCl2(PhN)(PMe3)3 shows a mer arrangement of phosphine and cis chloride ligands, one Irons to the phenylimido function. ... 

A differential technique is helpful in the analysis of organic compounds for traces of iron in the presence of interfering background absorption. The iron in the sample solution (solvent, 1+5 hydrochloric acid in methanol) is present as the strongly absorbing ferric chloride complex and exhibits an absorption band at 360 m/n. The reference liquid is equivalent to the sample solution except that phosphoric acid is substituted for hydrochloric. The iron phosphate complex is transparent. The phosphoric acid is presumed not to affect the spectrum of the organic background and the difference spectrum represents only the iron absorption. 

Spectrophotometric determination of the hole concentration Consider Cu as the hole in the sample, which is usually 1/3 of the total Cu. When a slight excess of iron(II) chloride solution is added to the powder dissolved in HCl, Fe(IlI) chloride and copper(II) chloride are formed. The latter represents the total Cu and the former is equivalent to Cu or hole concentration. Since the spectra of the two cations have well separated absorption maxima, the spectrophotometric method gives Cu(III) and total Cu in the same spectrum (see Sec. 16.5). 

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