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Decoupled spin crossover and structural phase transition in a molecular iron(II) complex

Cook, L.J.K., Shepherd, H.J., Comyn, T.P., Baldé, C., Cespedes, O., Chastanet, G., Halcrow, M.A. (2015) Decoupled spin crossover and structural phase transition in a molecular iron(II) complex. Chemistry - A European Journal, 21 (12). pp. 4805-4816. ISSN 0947-6539. (doi:10.1002/chem.201406307) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
http://dx.doi.org/10.1002/chem.201406307

Abstract

Crystalline [Fe(bppSMe) 2][BF4]2 (1 ; bppSMe = 4-(methylsulfanyl)-2,6-di(pyrazol-1-yl)pyridine) undergoes an abrupt spin-crossover (SCO) event at 265 ±5 K. The crystals also undergo a separate phase transition near 205 K, involving a contraction of the unit-cell a axis to one-third of its original value (high-temperature phase 1; Pbcn, Z = 12; lowtemperature phase 2; Pbcn, Z = 4). The SCO-active phase 1 contains two unique molecular environments, one of which appears to undergo SCO more gradually than the other. In contrast, powder samples of 1 retain phase 1 between 140-300 K, although their SCO behaviour is essentially identical to the single crystals. The compounds [Fe(bppBr)2][BF4]2 (2; bppBr = 4-bromo-2,6-di(pyrazol-1-yl)pyridine) and [Fe(bppI)2] [BF4]2 (3 ; bppI = 4-iodo-2,6-di(pyrazol-1-yl)-pyridine) exhibit more gradual SCO near room temperature, and adopt phase 2 in both spin states. Comparison of 1-3 reveals that the more cooperative spin transition in 1, and its separate crystallographic phase transition, can both be attributed to an intermolecular steric interaction involving the methylsulfanyl substituents. All three compounds exhibit the lightinduced excited-spin-state trapping (LIESST) effect with T(LIESST = 70-80 K), but show complicated LIESST relaxation kinetics involving both weakly cooperative (exponential) and strongly cooperative (sigmoidal) components. ©2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Item Type: Article
DOI/Identification number: 10.1002/chem.201406307
Additional information: Unmapped bibliographic data: LA - English [Field not mapped to EPrints] J2 - Chem. Eur. J. [Field not mapped to EPrints] AD - School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, United Kingdom [Field not mapped to EPrints] AD - Department of Chemistry, University of Bath, Claverton Down, Bath, United Kingdom [Field not mapped to EPrints] AD - Institute for Materials Research, School of Chemical and Process Engineering, University of Leeds, Leeds, United Kingdom [Field not mapped to EPrints] AD - University of Ziguinchor, Sciences and Technology Department, 253 Ziguinchor, Senegal [Field not mapped to EPrints] AD - CNRS, Univ. Bordeaux, ICMCB, UPR 9048, Pessac, France [Field not mapped to EPrints] AD - School of Physics and Astronomy, University of Leeds, E.C. Stoner Building, Leeds, United Kingdom [Field not mapped to EPrints] DB - Scopus [Field not mapped to EPrints]
Uncontrolled keywords: Crystal engineering, Iron, N-ligands, Photomagnetic properties, Spin crossover, Crystal engineering, Excited states, Iron, Pyridine, Single crystals, Spin dynamics, Crystallographic phase, High temperature phase, Light-induced excited spin-state trapping, Molecular environment, N ligands, Photomagnetic properties, Spin crossovers, Structural phase transition, Iron compounds
Subjects: Q Science > QD Chemistry > QD478 Solid State Chemistry
Q Science > QD Chemistry > QD473 Physical properties in relation to structure
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Giles Tarver
Date Deposited: 09 Oct 2015 10:26 UTC
Last Modified: 29 May 2019 16:06 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/50809 (The current URI for this page, for reference purposes)
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