A mononuclear iron(II) complex: cooperativity, kinetics and activation energy of the solvent-dependent spin transition

A mononuclear iron(II) complex: cooperativity, kinetics and activation energy of the solvent-dependent spin transition Full article

Journal

Dalton Transactions
ISSN: 1477-9226 , E-ISSN: 1477-9234

Output data

Year: 2016, Volume: 45, Number: 1, Pages: 107-120 Pages count : 14 DOI: 10.1039/c5dt03750f

Authors

Bushuev Mark B. ^1,2 , Pishchur Denis P. ¹ , Logvinenko Vladimir A. ^1,2 , Gatilov Yuri V. ^2,3 , Korolkov Ilya V. ^1,2 , Shundrina Inna K. ^2,3 , Nikolaenkova Elena B. ³ , Krivopalov Viktor P. ³

Affiliations

1	(Данные Web of science) Russian Acad Sci, Siberian Branch, Nikolaev Inst Inorgan Chem, Novosibirsk 630090, Russia
2	(Данные Web of science) Novosibirsk State Univ, Novosibirsk 630090, Russia
3	(Данные Web of science) Russian Acad Sci, Siberian Branch, NN Vorozhtsov Novosibirsk Inst Organ Chem, Novosibirsk 630090, Russia

The system [FeL2](BF4)(2) (1)-EtOH-H2O (L is 4-(3,5-dimethyl-1H-pyrazol-1-yl)-2-(pyridin-2-yl)-6-methylpyrimidine) shows a complicated balance between the relative stabilities of solvatomorphs and polymorphs of the complex [FeL2](BF4)(2). New solvatomorphs, 1(LS)center dot EtOH center dot H2O and beta-1(LS)center dot xH(2)O, were isolated in this system. They were converted into four daughter phases, 1(A/LS), 1(D/LS), 1(E/LS)center dot yEtOH center dot zH(2)O and 1(F/LS). On thermal cycling in sealed ampoules, the phases 1(LS)center dot EtOH center dot H2O and beta-1(LS)center dot xH(2)O transform into the anhydrous phase 1(A/LS). The hysteresis loop width for the 1(A/LS) <-> 1(A/HS) spin transition depends on the water and ethanol contents in the ampoule and varies from ca. 30 K up to 145 K. The reproducible hysteresis loop of 145 K is the widest ever reported one for a spin crossover complex. The phase 1(A/LS) combines the outstanding spin crossover properties with thermal robustness allowing for multiple cycling in sealed ampoules without degradation. The kinetics of the 1(A/LS) -> 1(A/HS) transition is sigmoidal which is indicative of strong cooperative interactions. The cooperativity of the 1(A/LS) -> 1(A/HS) transition is related to the formation of a 2D supramolecular structure of the phase 1(A/LS). The activation energy for the spin transition is very high (hundreds of kJ mol(-1)). The kinetics of the 1(A/HS) -> 1(A/LS) transition can either be sigmoidal or exponential depending on the water and ethanol contents in the ampoule. The phases 1(D/LS) and 1(F/LS) show gradual crossover, whereas the phase 1(E/LS)center dot yEtOH center dot yH(2)O shows a reversible hysteretic transition associated with the solvent molecule release and uptake.

Bushuev M.B. , Pishchur D.P. , Logvinenko V.A. , Gatilov Y.V. , Korolkov I.V. , Shundrina I.K. , Nikolaenkova E.B. , Krivopalov V.P.
A mononuclear iron(II) complex: cooperativity, kinetics and activation energy of the solvent-dependent spin transition
Dalton Transactions. 2016. V.45. N1. P.107-120. DOI: 10.1039/c5dt03750f WOS Scopus РИНЦ

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Scopus	2-s2.0-84969837166
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