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628 results on '"Romanenko, G. V."'

12. METAL-ORGANIC FRAMEWORKS IN RUSSIA: FROM THE SYNTHESIS AND STRUCTURE TO FUNCTIONAL PROPERTIES AND MATERIALS

Author

Agafonov, M. A., Alexandrov, E. V., Artyukhova, N. A., Bekmukhamedov, G. E., Blatov, V. A., Butova, V. V., Gayfulin, Y. M., Garibyan, A. A., Gafurov, Z. N., Gorbunova, Yu. G., Gordeeva, L. G., Gruzdev, M. S., Gusev, A. N., Denisov, G. L., Dybtsev, D. N., Enakieva, Yu. Yu., Kagilev, A. A., Kantyukov, A. O., Kiskin, M. A., Kovalenko, K. A., Kolker, A. M., Kolokolov, D. I., Litvinova, Y. M., Lysova, A. A., Maksimchuk, N. V., Mironov, Y. V., Nelyubina, Yu. V., Novikov, V. V., Ovcharenko, V. I., Piskunov, A. V., Polyukhov, D. M., Polyakov, V. A., Ponomareva, V. G., Poryvaev, A. S., Romanenko, G. V., Soldatov, A. V., Solovyeva, M. V., Stepanov, A. G., Terekhova, I. V., Trofimova, O. Yu., Fedin, V. P., Fedin, M. V., Kholdeeva, O. A., Tsivadze, A. Yu., Chervonova, U. V., Cherevko, A. I., Shul′gin, V. F., Shutova, E. S., and Yakhvarov, D. G.

Published
2022
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19. Synthesis, Structure, and Magnetic Properties of the Cu(hfac)2 Complex with a Dichlorophenyl-Substituted Nitronylnitroxyl.

Author

Artiukhova, N. A., Tretyakov, E. V., Smirnova, K. A., Letyagin, G. A., Romanenko, G. V., and Bogomyakov, A. S.

Subjects
COPPER, MAGNETIC structure, MAGNETIC susceptibility, MAGNETIC properties, CRYSTAL structure, NITROXIDES
Abstract

A dichlorophenyl substituted nitronyl nitroxide radical 2-(2,6-dichlorophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (L) is prepared, its structure and magnetic properties are studied. It is shown that the interaction of bis(hexafluoroacetylacetonato)copper(II) [Cu(hfac)2] with L leads to the formation of the {[Cu(hfac)2][Cu(hfac)2L2]} heterospin complex whose crystal structure consists of pseudo-polymer chains formed by alternating single-spin [Cu(hfac)2] and three-spin [Cu(hfac)2L2] fragments. It is established that the temperature dependence of magnetic susceptibility of {[Cu(hfac)2][Cu(hfac)2L2]} is determined by ferromagnetic exchange interactions between unpaired electrons of Cu(II) ions and the axially coordinated L in three-spin fragments. [ABSTRACT FROM AUTHOR]

Published
2024
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28. Interplay between lattice, orbital, and magnetic degrees of freedom in the chain-polymer Cu(II) breathing crystals

Author

Streltsov, S. V., Petrova, M. V., Morozov, V. A., Romanenko, G. V., Anisimov, V. I., and Lukzen, N. N.

Subjects
Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science, Physics - Chemical Physics
Abstract

The chain-polymer Cu(II) breathing crystals C21H19CuF12N4O6 were studied using the x-ray diffraction and ab initio band structure calculations. We show that the crystal structure modification at T=146 K, associated with the spin crossover transition, induces the changes of the orbital order in half of the Cu sites. This in turn results in the switch of the magnetic interaction sign in accordance with the Goodenough-Kanamori-Andersen theory of the coupling between the orbital and spin degrees of freedom., Comment: 6 pages, 7 figures

Published
2012
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29. Crystal Structure, Microhardness and Thermal Expansion of Ternary TaIr2B2 Boride.

Author

Lozanov, V. V., Utkin, A. V., Letyagin, G. A., Romanenko, G. V., Polyukhov, D. M., Kozlova, S. G., Titov, A. T., and Baklanova, N. I.

Subjects
THERMAL expansion, CRYSTAL structure, BORIDES, X-ray powder diffraction, MICROHARDNESS
Abstract

The ternary TaIr2B2 boride was prepared by the reaction between iridium and TaB2 powders. It was shown that a choice in favor of any crystal structure of TaIr2B2 boride using only X-ray powder diffraction analysis and single-crystal XRD is rather difficult to make. The DFT calculations were carried out to predict the energetically preferred crystal structure of TaIr2B2. The 11B solid-state NMR spectrum of TaIr2B2 was recorded for the first time. A combination of diffraction and spectroscopic methods, as well as theoretical calculations, allowed us to make clear choice in favor of the triclinic space group for the crystal structure of TaIr2B2. The Vickers microhardness value for TaIr2B2 was found to be 17.9 ± 2.3 GPa, and the ternary TaIr2B2 boride can be considered a hard material. Therefore, the family of hard ternary boride phases got a new member. The coefficients of thermal expansion of TaIr2B2 measured by in situ high-temperature XRD analysis are independent of temperature along the a and b axes, but the CTE along the c axis deviates noticeably at elevated temperatures. The findings for the new ternary TaIr2B2 boride are of interest for the rational design of complex structural materials containing Ta–Ir–B-based components and prediction of their high-temperature behavior. Further research into this ternary boride as well as other iridium-containing ternary borides will provide a tool to solve the problems faced by high-temperature materials science. [ABSTRACT FROM AUTHOR]

Published
2024
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34. Diversity of Structural Motifs in Cu(hfac)2 Complexes with Spin-Labeled Polyalkylpyrazoles.

Author

Fokin, S. V., Chubakova, E. T., Tolstikov, S. E., Romanenko, G. V., Smirnova, K. A., Bogomyakov, A. S., and Ovcharenko, V. I.

Subjects
COORDINATION polymers, COPPER, COORDINATION polymers synthesis, NITROXIDES, SPIN crossover, SINGLE crystals
Abstract

The extension of a series of polyalkylpyrazolyl-substituted 2-imidazoline nitronyl nitroxide radicals LR1/R2/R3 (R = Me, Et, Pr, Bu) enables the synthesis of a number of coordination polymers based on copper(II) bis(hexafluoroacetylacetonate) Cu(hfac)2 with LR1/R2/R3. As compared to breathing crystals (Cu(hfac)2 complexes with monoalkyl-substituted nitroxides LR1 with bridging μ2-O,N coordination), the introduction of the second substituent LR1/R2 into the pyrazole ring allows the performance of the tritopic function of the paramagnetic ligand (μ3-O,O,N) and the formation of 1D and 2D polymers with original structures and different combinations of [CuO6], [CuO5N], [CuO4N2], and [CuO5] coordination cores. Only molecular complexes are obtained with single 3-substituted nitroxide LR1/R2/R3–LMe3. The single crystal X-ray diffraction study of the structures of these compounds shows that as in the case of LMe3, an increase in the size of one of substituents in LR1/R2 to Pr or Bu causes an increase in distances between paramagnetic centers in two- and three-spin exchange clusters, and correspondingly, spin transitions are absent. [ABSTRACT FROM AUTHOR]

Published
2024
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44. Synthesis, Structure, and Magnetic Properties of Cu(hfac)2 Polymeric Complexes with Cyanophenyl-Substituted Nitroxyls.

Author

Artyukhova, N. A., Zargarova, L. V., Romanenko, G. V., Bogomyakov, A. S., and Ovcharenko, V. I.

Subjects
COPPER, MAGNETIC properties, MAGNETIC structure, NITROXYL, FERROMAGNETIC materials
Abstract

Spirocyclopentyl derivatives of cyanophenyl-substituted nitroxyl radicals (2-(4′-cyanophenyl)-4,5-bis(spirocyclopentyl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (NN) and the corresponding iminonitroxyl 2-(4′-cyanophenyl)-4,5-bis(spirocyclopentyl)-4,5-dihydro-1H-imidazole-1-oxyl (IN)) are synthesized; their structure and magnetic properties are studied. Interaction of IN and NN with bis(hexafluoroacetylacetonato) copper(II) [Cu(hfac)2] leads to the formation of heterospin chain polymeric {[Cu(hfac)2]2(IN)}, {[Cu(hfac)2]3(NN)2}, and layered {[Cu(hfac)2]3(NN)2}·C7H16 complexes. It is shown that the layered {[Cu(hfac)2]3(NN)2}·C7H16 is a soft ferromagnet that transforms into a magnetically ordered state at helium temperatures. [ABSTRACT FROM AUTHOR]

Published
2023
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