Mössbauer Spectroscopic Study Of An Iron(III) Complex With Crown Porphyrin

Plots of the relative areas (A refers to the left scale) and intensities (B refers to the right scale) of (1) the doublet and (2) the extended absorption vs. the temperature

Mössbauer Spectroscopic Study Of An Iron(III) Complex With Crown Porphyrin. Pankratov D.A., Stukan R.A., Al'Ansari Ya.-F., Savinkina E.V., Kiselev Yu.M. //Russian Journal of Inorganic Chemistry. 2011. V. 56. № 10. P. 1603-1608

A complex of 57Fe with 5-{4-[((4′-hydroxybenzo-15-crown-5)-5′-yl)diazo]phenyl}-10,15,20-triphenylporphyrin was studied by Mössbauer spectroscopy. The presence of signals of two types in the spectra (a doublet and an extended absorption band over a wide velocity range) suggests that the Fe atoms occupy two structurally different positions in this complex. The dependences of the doublet asymmetry on temperature and the angle between the normal to the sample plane and the γ-ray beam were studied. The isomer shift δ of the doublet in the temperature range from 360 to 5 K changes from 0.25 to 0.41 mm/s, while the quadrupole splitting remains virtually unchanged (Δ ≈ 0.65 mm/s). The relaxation-type absorption over a wide velocity range, the relative area of which strongly varies with temperature, can be described by a broad singlet with the following parameters: δ = 0.30–0.44 mm/s and Γ = 2.8–3.38 mm/s. According to the δ values, both signals are due to Fe(III) derivatives.

The structures and properties of metalloporphyrins (MPs), such as hemoglobin, chlorophyll, and vitamin В12, involved in vital processes depend on the complexing metal and the peripheral substituents. A great number of MPs are chemically inert and thermally stable, have high molar absorption coefficients in the UV-Vis and near-IR ranges, and show reversible redox transitions. This accounts for the interest in comprehensive study of the corresponding properties using a variety of physicochemical techniques.

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New Platinum Superoxo Complex

Evolution of the VIS-spectra of the pink solutions in time

New Platinum Superoxo Complex. Kiselev Yu.M., Pankratov D.A., Shundrin L.A., Kiseleva I.N. //Russian Journal of Inorganic Chemistry. 1996. V. 41. № 12. P. 1963-1966Search the full text below. Ищи полный текст ниже.

Products of oxidation of Pt(IV) hexahydroxo complexes with ozone in alkali media have been studied with physicochemical methods (electron spectroscopy, EPR, and cyclic voltammetry). The oxidation product is pink at alkali concentration in solution higher than 5 mol/l. The pink complex represents previously undescribed platinum superoxo complex with a bridging O2- group.

Our previous study concerned the possibility of preparing platinum compounds in unusually high oxidation states from alka1ine solutions under the action of ozone. In that study, we detected a blue platinum superoxo complex of binuclear structure with the O2- bridging group. The bridge structure of this complex was supported by ESR, and the complex was show to form only at rather low alkalinity. At higher alkali concentrations (cOH- > 5 mol/l), a similar reaction results in a pale pink complex containing oxidizer.

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Ab Initio Calculations Of Hydroxoplatinum Compounds: II. Binuclear Platinum(IV) Superoxo Complexes

Equilibrium structure of the binuclear monobridged platinum superoxo complexes [(OH)5Pt(μ-O2)Pt(OH)5]3–Ab Initio Calculations Of Hydroxoplatinum Compounds: II. Binuclear Platinum(IV) Superoxo Complexes. Pankratov D.A., Dement'ev A.I., Kiselev Yu.M. //Russian Journal of Inorganic Chemistry. 2008. V.53. №2. P.247-253.Search the full text below. Ищи полный текст ниже.

The structural and spectral data have been obtained by ab initio methods for the [(OH)4Pt(μ-O2)(μ-OH)Pt(OH)4]2-, [(OH)4Pt(μ-O2)(μ-OH)Pt(OH)4(OH)]3-, [(OH)5Pt(μ-O2)Pt(OH)5]3-, and [(H2O)(OH)4Pt(μ-O2)Pt(OH)4•(H2O)]- clusters, corresponding to binuclear platinum (IV) superoxo complexes with one and two bridges. The data obtained are in good agreement with experimental data and make it possible to judge the structure of available complexes.

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EPR Spectra Of Solutions Of Platinum Superoxo Hydroxo Complexes

EPR Spectra Of Solutions Of Blue Platinum Superoxo Hydroxo Complexes EPR Spectra Of Solutions Of Pink Platinum Superoxo Hydroxo Complexes

EPR Spectra Of Solutions Of Platinum Superoxo Hydroxo Complexes. Komozin P.N., Pankratov D.A., Kiselev Yu.M. //Russian Journal of Inorganic Chemistry. 1999. V. 44. № 12. P. 1945-1951Search the full text below. Ищи полный текст ниже.

EPR spectra of platinum superoxo hydroxo complexes in alkaline solutions were studied at various alkali concentrations. The EPR parameters for new platinum complexes were determined; the g-factors and hyperfine coupling constants were interpreted in terms of the ligand field theory. The structure of the platinum coordination sphere in the superoxo hydroxo complexes is discussed based on the EPR data.

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