Potassium hexahydroperoxostannate: synthesis and structure. Ippolitov E.G., Tripol'skaya T.A., Prikhodchenko P.V., Pankratov D.A. //Russian Journal of Inorganic Chemistry. 2001. V.46. №6. P.851-857
Polycrystalline potassium hexahydroperoxostannate was prepared by replacement of hydroxo groups in potassium hexahydroxostannate upon its dissolution in hydrogen peroxide. A comparative study of the product and the starting hydroxostannate by powder X-ray diffraction analysis, thermogravimetry, and IR, 2H, 39K, and 119Sn NMR, and Mössbauer spectroscopy was carried out. The peroxo compound K2Sn(OOH)6 crystallizes in the hexagonal system with a = 7.264(7) Å, c = 10.168(4) Å. IR, NMR, and Mössbauer spectroscopy data show that the tin coordination polyhedron in the peroxo compound is an octahedron formed by the coordinated hydroperoxo groups.
Previously, sodium hexahydroperoxostannate was prepared and characterized by powder X-ray diffraction analysis, thermogravimetry, IR, 1H NMR, and Mossbauer spectroscopy, and by thermodynamic and kinetic method. The tin atom in this compound were found to occur in the octahedral environment of hydroperoxo group. It appeared pertinent to confirm the possibility of formation of this type of tin compound by preparing a new hydroperoxo complex. To this end, we performed the first synthesis of potassium hexahydroperoxostannate. Comparative study of potassium hexahydrosstannate (1) and hexahydroperoxosstannate (2) and their deuterated analogue (1a and 2a, respectively) was carried out by powder X-ray diffraction analysis, thermogravimetry, and IR, NMR (2H, 39K and 119Sn), and Mossbauer spectroscopy.
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Investigation Of Iron(III) Complex With Crown-Porphyrin. Pankratov D.A., Dolzhenko V.D., Kiselev Y.M., Stukan R.A., Al Ansari Y.F., Savinkina E.V. //Hyperfine Interactions. 2013. V.222. Is.1 (Suppl). P. S1-S11
Iron complex of 5-(4-(((4′-hydroxy-benzo-15-crown-5)-5′-yl)diazo)phenyl)-10,15,20-triphenylporphyrin was investigated by 57Fe Mössbauer spectroscopy and EPR. Two Fe sites were identified; they give two differing signals, doublet and wide absorption in a large velocity interval. EPR spectra of solutions of the complex in chloroform at room temperature also show two signals with g = 2.064, AFe = 0.032 cm− 1; g = 2.015, AFe = 0.0034 cm− 1. The doublet asymmetry is studied vs. temperature and normal angle to the sample plane and gamma-beam. The isomer shift δ in the doublet varies from 0.41 to 0.25 mm/s in the 5÷360 K temperature range, whereas quadruple splitting value is constant, Δ ∼ 0.65 mm/s. The relax absorption may be described as a wide singlet (δ = 0.30 ÷ 0.44 mm/s and Γ = 2.83 ÷ 3.38 mm/s); its relative area strongly depends on temperature. According to δ, both signals are assigned to Fe(III).
Structures and properties of metal porhyrins (MPs) (hemoglobin, chlorophyll, vitamin B12, etc.) participating in vital processes depend on a central metal and peripheral substituents. Most MPs possess chemical and thermal stability, high extinctions coefficients in UV, visible and near IR ranges and reversible red-ox transitions. Therefore, detail study of their properties with the use of various physicochemical methods is of interest.
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As a rule, interpretation of poorly resolved Mössbauer spectra is an intricate, multiparametric problem. A measured spectrum is fitted using a particular model based on available information about the composition, structure, and properties of the sample. A criterion for whether the spectrum has been adequately decomposed into components is the agreement between the obtained parameters and expected ones for realistic physical and chemical models. A criterion for sufficiency is provided by statistical parameters of the deviation of results of the proposed model from experimental data. Clearly, a larger number of subspectra in a model and a smaller number of constraints for their components ensure better fitting quality. In some cases, when the iron atoms in a sample have an inhomogeneous environment and parameters of subspectra vary continuously in some range, or spectra contain overlapping components (resonance lines), a model-free description of spectra is used, instead of models. However, a model-free description of spectra also requires an adequate initial hypothesis as to the properties of the substance to be studied. In some cases, even with well-resolved spectra, an incorrect initial hypothesis may entail inadequate interpretation of experimental data.
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