Relationship between phase transition temperature and accessible volume for substituent in Cu(hfac)2 chain-polymer complexes with pyridine-based nitroxides

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Relationship between phase transition temperature and accessible volume for substituent in Cu(hfac)₂ chain-polymer complexes with pyridine-based nitroxides. / Tolstikov, Svyatoslav; Smirnova, Kristina; Kolesnikov, Andrey et al.

In: Polyhedron, Vol. 230, 116212, 15.01.2023.

Research output: Contribution to journal › Article › peer-review

BibTeX

@article{ba8d40789f20449fb5c124cde0efbb4d,

title = "Relationship between phase transition temperature and accessible volume for substituent in Cu(hfac)2 chain-polymer complexes with pyridine-based nitroxides",

abstract = "Reaction of Cu(hfac)2 with pyridyl-substituted nitronyl nitroxides yielded chain-polymer complexes {[Cu(hfac)2LR]2[Cu(hfac)2]}∞, where LR – 2-(4-R-pyridin-3-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, R = Me, MeO, Et, n-Pr, i-Pr, n-Bu, and CP (cyclopentyl). X-ray crystallography experiments proved that the solid state of the investigated compounds has centrosymmetric dimers [Cu(hfac)2LR]2 bonded by the Cu(hfac)2 fragments into chain polymers. The environment of the Cu atoms in the dimeric fragments undergoes structural rearrangement upon temperature variation. Such transformations cause anomalous temperature dependences of µeff. We established the relationship between the phase transition temperature and the amount of space accessible for pyridine substituent R. In the complexes containing LMe, LMeO, Ln-Bu, and LCP substituents R occupy relatively small amount of space, which results in ordering of R and high transition temperatures of these complexes, whereas the presence of the accessible volume for the substituent disordering leads to increased entropy of the high temperature phase, and, therefore, decreased transition temperature of the complexes with LEt, Li-Pr, and Ln-Pr.",

keywords = "Chain polymers, Cu(II) complexes, Magneto–structural correlations, Nitronyl nitroxide radicals",

author = "Svyatoslav Tolstikov and Kristina Smirnova and Andrey Kolesnikov and Gleb Letyagin and Artem Bogomyakov and Galina Romanenko and Victor Ovcharenko",

note = "Funding Information: This research was financially supported by the Russian Science Foundation (grant 18-13-00380 ). Publisher Copyright: {\textcopyright} 2022 Elsevier Ltd",

year = "2023",

month = jan,

day = "15",

doi = "10.1016/j.poly.2022.116212",

language = "English",

volume = "230",

journal = "Polyhedron",

issn = "0277-5387",

publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Relationship between phase transition temperature and accessible volume for substituent in Cu(hfac)2 chain-polymer complexes with pyridine-based nitroxides

AU - Tolstikov, Svyatoslav

AU - Smirnova, Kristina

AU - Kolesnikov, Andrey

AU - Letyagin, Gleb

AU - Bogomyakov, Artem

AU - Romanenko, Galina

AU - Ovcharenko, Victor

PY - 2023/1/15

Y1 - 2023/1/15

N2 - Reaction of Cu(hfac)2 with pyridyl-substituted nitronyl nitroxides yielded chain-polymer complexes {[Cu(hfac)2LR]2[Cu(hfac)2]}∞, where LR – 2-(4-R-pyridin-3-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, R = Me, MeO, Et, n-Pr, i-Pr, n-Bu, and CP (cyclopentyl). X-ray crystallography experiments proved that the solid state of the investigated compounds has centrosymmetric dimers [Cu(hfac)2LR]2 bonded by the Cu(hfac)2 fragments into chain polymers. The environment of the Cu atoms in the dimeric fragments undergoes structural rearrangement upon temperature variation. Such transformations cause anomalous temperature dependences of µeff. We established the relationship between the phase transition temperature and the amount of space accessible for pyridine substituent R. In the complexes containing LMe, LMeO, Ln-Bu, and LCP substituents R occupy relatively small amount of space, which results in ordering of R and high transition temperatures of these complexes, whereas the presence of the accessible volume for the substituent disordering leads to increased entropy of the high temperature phase, and, therefore, decreased transition temperature of the complexes with LEt, Li-Pr, and Ln-Pr.

AB - Reaction of Cu(hfac)2 with pyridyl-substituted nitronyl nitroxides yielded chain-polymer complexes {[Cu(hfac)2LR]2[Cu(hfac)2]}∞, where LR – 2-(4-R-pyridin-3-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, R = Me, MeO, Et, n-Pr, i-Pr, n-Bu, and CP (cyclopentyl). X-ray crystallography experiments proved that the solid state of the investigated compounds has centrosymmetric dimers [Cu(hfac)2LR]2 bonded by the Cu(hfac)2 fragments into chain polymers. The environment of the Cu atoms in the dimeric fragments undergoes structural rearrangement upon temperature variation. Such transformations cause anomalous temperature dependences of µeff. We established the relationship between the phase transition temperature and the amount of space accessible for pyridine substituent R. In the complexes containing LMe, LMeO, Ln-Bu, and LCP substituents R occupy relatively small amount of space, which results in ordering of R and high transition temperatures of these complexes, whereas the presence of the accessible volume for the substituent disordering leads to increased entropy of the high temperature phase, and, therefore, decreased transition temperature of the complexes with LEt, Li-Pr, and Ln-Pr.

KW - Chain polymers

KW - Cu(II) complexes

KW - Magneto–structural correlations

KW - Nitronyl nitroxide radicals

UR - http://www.scopus.com/inward/record.url?scp=85142745053&partnerID=8YFLogxK

U2 - 10.1016/j.poly.2022.116212

DO - 10.1016/j.poly.2022.116212

M3 - Article

AN - SCOPUS:85142745053

VL - 230

JO - Polyhedron

JF - Polyhedron

SN - 0277-5387

M1 - 116212

ER -

ID: 39997025