title: A Copper-Nitroxide Adduct Exhibiting Separate Single Crystal-to-Single Crystal Polymerization-Depolymerization and Spin Crossover Transitions.
abstract: A complex cascade of solid-state processes initiated by variation of temperature was found for the heterospin complex [Cu(hfac)2L(Me/Et)] formed in the reaction of copper(II) hexafluoroacetylacetonate [Cu(hfac)2] with stable nitronyl nitroxide 2-(1-methyl-3-ethyl-1H-pyrazol-4-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (L(Me/Et)). The cooling of the compound below 260 K initiated a solid-state chemical reaction, which led to a depolymerization of chains and formation of a pair heterospin complex [Cu(hfac)2L(Me/Et)2][[Cu(hfac)2]3L(Me/Et)2]. Further decrease in temperature below 144 K led to a spin transition accompanied by a drastic decrease in the effective magnetic moment from 2.52 to 2.24 μB. When the compound was heated, the order of effects was reversed: at first, the magnetic moment abruptly increased, and then the molecular fragments of the pair cluster united into polymer chains. Two hysteresis loops correspond to this cascade of temperature-induced structural transformations on the experimental dependence μeff(T): one at high (T↑ = 283 K and T↓ = 260 K) and the other at low (T↑ = 161 K, T↓ = 144 K) temperature. The spin transitions were also recorded for the [[Cu(hfac)2]3L(Bu/Et)2] and [[Cu(hfac)2]5L(Bu/Et)4] molecular complexes, which are models of the trinuclear fragment of the {[Cu(hfac)2]3L(Me/Et)2} pair cluster.
authors.affiliation: International Tomography Center, SB RAS , Institutskaya Str., 3a Novosibirsk 630090, Russian Federation.
authors.forename: Victor
authors.initials: V
authors.lastname: Ovcharenko
authors.affiliation: International Tomography Center, SB RAS , Institutskaya Str., 3a Novosibirsk 630090, Russian Federation.
authors.forename: Sergey
authors.initials: S
authors.lastname: Fokin
authors.affiliation: International Tomography Center, SB RAS , Institutskaya Str., 3a Novosibirsk 630090, Russian Federation.
authors.forename: Elvina
authors.initials: E
authors.lastname: Chubakova
authors.affiliation: International Tomography Center, SB RAS , Institutskaya Str., 3a Novosibirsk 630090, Russian Federation.
authors.forename: Galina
authors.initials: G
authors.lastname: Romanenko
authors.affiliation: International Tomography Center, SB RAS , Institutskaya Str., 3a Novosibirsk 630090, Russian Federation.
authors.forename: Artem
authors.initials: A
authors.lastname: Bogomyakov
authors.affiliation: N. S. Kurnakov Institute of General and Inorganic Chemistry, RAS , 31 Leninsky Ave., Moscow 119991, Russian Federation.
authors.forename: Zhanna
authors.initials: Z
authors.lastname: Dobrokhotova
authors.affiliation: International Tomography Center, SB RAS , Institutskaya Str., 3a Novosibirsk 630090, Russian Federation.
authors.forename: Nikita
authors.initials: N
authors.lastname: Lukzen
authors.affiliation: International Tomography Center, SB RAS , Institutskaya Str., 3a Novosibirsk 630090, Russian Federation.
authors.forename: Vitaly
authors.initials: V
authors.lastname: Morozov
authors.affiliation: International Tomography Center, SB RAS , Institutskaya Str., 3a Novosibirsk 630090, Russian Federation.
authors.forename: Marina
authors.initials: M
authors.lastname: Petrova
authors.affiliation: Kazan National Research Technological University , 68 K. Marx Str., Kazan 420015, Russian Federation.
authors.forename: Maria
authors.initials: M
authors.lastname: Petrova
authors.affiliation: Kazan National Research Technological University , 68 K. Marx Str., Kazan 420015, Russian Federation.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Zueva
authors.affiliation: A. E. Favorsky Irkutsk Institute of Chemistry, SB RAS , 1 Favorsky Str., Irkutsk 664033, Russian Federation.
authors.forename: Igor
authors.initials: I
authors.lastname: Rozentsveig
authors.affiliation: A. E. Favorsky Irkutsk Institute of Chemistry, SB RAS , 1 Favorsky Str., Irkutsk 664033, Russian Federation.
authors.forename: Elena
authors.initials: E
authors.lastname: Rudyakova
authors.affiliation: A. E. Favorsky Irkutsk Institute of Chemistry, SB RAS , 1 Favorsky Str., Irkutsk 664033, Russian Federation.
authors.forename: Galina
authors.initials: G
authors.lastname: Levkovskaya
authors.affiliation: Kazan (Volga Region) Federal University , 18 Kremlevskaya Str., Kazan 420008, Russian Federation.
authors.forename: Renad
authors.initials: R
authors.lastname: Sagdeev