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Murav'ev V.I.,Research and Production Enterprise Izmeritel
Russian Journal of Coordination Chemistry/Koordinatsionnaya Khimiya | Year: 2010

Experimental EPR data for copper(II) complexes with liquid-crystal poly(propylenimine) dendrimers were analyzed. The influence of the pseudotetrahedral distortion of the nearest environment of the copper ion on the parameters of the EPR spectra was considered. The covalent bond parameters were calculated from the EPR data. The dependence of the delocalization of the unpaired electron of the copper ion on the pseudotetrahedral distortion of its coordination unit was determined. The behavior of the Zeeman coupling parameters was discussed. Various contributions to the components of the hyperfine coupling (HFC) tensor were calculated. The causes of the changes in the HFC parameters in the distorted complexes were discussed. © Pleiades Publishing, Ltd., 2010.


Murav'Ev V.I.,Research and Production Enterprise Izmeritel
Russian Journal of Coordination Chemistry/Koordinatsionnaya Khimiya | Year: 2010

The structures of high-spin iron(III) complexes with poly(propylenimine) dendrimers were examined by EPR spectroscopy. The pseudotetrahedral distortion of the coordination unit (CU) was considered. The fine structure parameters (FSPs) of the EPR spectra were analyzed. A dependence of the FSPs on the CU distortion and the covalent bonding was established. The influence of the axial Cl atoms on FSPs was considered. Splitting of the quartet term caused by the orthorhombic CU distortion with a pseudotetrahedral structure was estimated from the EPR data. © 2010 Pleiades Publishing, Ltd.


Murav'ev V.I.,Research and Production Enterprise Izmeritel
Russian Journal of Coordination Chemistry/Koordinatsionnaya Khimiya | Year: 2011

The electronic structures of the low-symmetry complexes of 4s 1-67Zn+, 5s 1-111Cd +, and 6s 1-205Tl2+ ions in isostructural crystals of potassium sulfate, rubidium sulfate, and potassium selenate were studied by the EPR data. The sp-mixing of the atomic orbitals of the paramagnetic ion in the molecular orbital of the ground state was established. The parameters of the EPR spectra were analyzed. The sp-mixing was shown to result in negative shifts of the Zeeman interaction parameters. The signs of components of the hyperfine coupling tensor (A tensor) were considered. The determining role of the contribution from the isotropic hyperfine coupling to the components of the A tensor was found. The anomalously low observed values of the hyperfine coupling parameters of the thallium complexes were interpreted. © 2011 Pleiades Publishing, Ltd.


Murav'ev V.I.,Research and Production Enterprise Izmeritel
Russian Journal of Coordination Chemistry/Koordinatsionnaya Khimiya | Year: 2011

The structures of the spin-variable iron(III) complexes Fe(4-OCH 3-SalEen) 2X and FeL′ 2X (L′ is oxysalicylidene-N′-ethyl-N-ethylenediamine; X = PF 6, NO 3, and SCN) were examined from their EPR spectra. The coordination units (CUs) of these complexes are a high-symmetry octahedron with a slight tetrahedral distortion or a low-symmetry pseudooctahedron with considerable tetragonal and orthorhombic distortions. When the complex passes from the high-spin to low-spin state, its CU changes. The energy level splittings caused by various types of distortions were estimated from the EPR data. The distortion of the CU depends on the outer-sphere anion. The magnetic resonance parameters of the complexes were analyzed. The fine structure parameters of the EPR spectra of high-spin complexes (the ground-state term is 6A 1g) depend on the CU distortion and the covalent bonding. The spin-orbital coupling makes an appreciable second-order contribution to the expressions for the Zeeman coupling parameters of low-spin complexes (the ground-state term is 2T 2g). © 2011 Pleiades Publishing, Ltd.

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