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Pressure effect studies on the spin-transition behavior of a dinuclear iron(II) compound

Pressure effect studies on the spin-transition behavior of a dinuclear iron(II) compound
Pressure effect studies on the spin-transition behavior of a dinuclear iron(II) compound
Magnetic studies into the effect of different hydrostatic pressures between ambient and 1.03 GPa on the high-spin (HS) ? low-spin (LS) transition behavior of the dinuclear iron(II) compound [FeII2(PMAT)2](BF4)4·DMF (1, PMAT = 4-amino-3,5-bis{[(2-pyridylmethyl)amino]methyl}-4H-1,2,4-triazole, DMF = N,N-dimethylformamide) have been carried out at 2–300 K. Under ambient pressure, the sample studied exhibits a [HS–HS] to [HS–LS] half spin transition (ST) at T = 208 K without any thermal hysteresis. Increasing the pressure above 0.2 GPa causes an increase (initially rapid but above 0.5 GPa more gradual) of T as well as a matching reduction in the residual high-spin fraction at room temperature. This paper probes in detail how the increased pressure favors the stabilization of the system through a transition from the [HS–HS] state to the [HS–LS] state, although there is no evidence of the [LS–LS] state even under a pressure of 1.03 GPa and down to 2 K. This work includes magnetic measurements, a calorimetric study of the ST behavior, and an estimation of the entropy change for such a half-ST process. The origin of [HS–HS] ? [HS–LS] transition behavior, which likely lies with the rigidness of the bridging ligand, is explained in greater detail. This is consistent with significant stabilization of the [HS–LS] form by the two very rigid bridging ligands between the two FeII centers. The role of intermolecular interactions in the stabilization of the dinuclear lattice system is established.
spin crossover, iron, n li­gands, high-pressure chemistry, calorimetry
1434-1948
843-849
Bhattacharjee, Ashis
75407b7c-33d9-43d3-9095-39df44196abd
Roy, Madhusudan
1cc1e1bd-ed31-4fa5-8c4e-43d8921999d8
Ksenofontov, Vadim
9b4497c7-16c3-49b6-a2fd-cfa061058ac3
Kitchen, Jonathan A.
3999f5cb-d53e-4c51-b750-627bd2a1b9b6
Brooker, Sally
2ee9681a-3ff7-41be-88c5-681f66b953ef
Gütlich, Philipp
e93db621-1175-46fe-80b0-d7791be2b353
Bhattacharjee, Ashis
75407b7c-33d9-43d3-9095-39df44196abd
Roy, Madhusudan
1cc1e1bd-ed31-4fa5-8c4e-43d8921999d8
Ksenofontov, Vadim
9b4497c7-16c3-49b6-a2fd-cfa061058ac3
Kitchen, Jonathan A.
3999f5cb-d53e-4c51-b750-627bd2a1b9b6
Brooker, Sally
2ee9681a-3ff7-41be-88c5-681f66b953ef
Gütlich, Philipp
e93db621-1175-46fe-80b0-d7791be2b353

Bhattacharjee, Ashis, Roy, Madhusudan, Ksenofontov, Vadim, Kitchen, Jonathan A., Brooker, Sally and Gütlich, Philipp (2013) Pressure effect studies on the spin-transition behavior of a dinuclear iron(II) compound. [in special issue: Spin-Crossover Complexes (Cluster Issue)] European Journal of Inorganic Chemistry, 2013 (5-6), 843-849. (doi:10.1002/ejic.201201522).

Record type: Article

Abstract

Magnetic studies into the effect of different hydrostatic pressures between ambient and 1.03 GPa on the high-spin (HS) ? low-spin (LS) transition behavior of the dinuclear iron(II) compound [FeII2(PMAT)2](BF4)4·DMF (1, PMAT = 4-amino-3,5-bis{[(2-pyridylmethyl)amino]methyl}-4H-1,2,4-triazole, DMF = N,N-dimethylformamide) have been carried out at 2–300 K. Under ambient pressure, the sample studied exhibits a [HS–HS] to [HS–LS] half spin transition (ST) at T = 208 K without any thermal hysteresis. Increasing the pressure above 0.2 GPa causes an increase (initially rapid but above 0.5 GPa more gradual) of T as well as a matching reduction in the residual high-spin fraction at room temperature. This paper probes in detail how the increased pressure favors the stabilization of the system through a transition from the [HS–HS] state to the [HS–LS] state, although there is no evidence of the [LS–LS] state even under a pressure of 1.03 GPa and down to 2 K. This work includes magnetic measurements, a calorimetric study of the ST behavior, and an estimation of the entropy change for such a half-ST process. The origin of [HS–HS] ? [HS–LS] transition behavior, which likely lies with the rigidness of the bridging ligand, is explained in greater detail. This is consistent with significant stabilization of the [HS–LS] form by the two very rigid bridging ligands between the two FeII centers. The role of intermolecular interactions in the stabilization of the dinuclear lattice system is established.

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More information

e-pub ahead of print date: 23 January 2013
Published date: February 2013
Keywords: spin crossover, iron, n li­gands, high-pressure chemistry, calorimetry
Organisations: Organic Chemistry: Synthesis, Catalysis and Flow

Identifiers

Local EPrints ID: 352611
URI: http://eprints.soton.ac.uk/id/eprint/352611
ISSN: 1434-1948
PURE UUID: 130de833-d89c-4209-aeb4-9c32330104bc
ORCID for Jonathan A. Kitchen: ORCID iD orcid.org/0000-0002-7139-5666

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Date deposited: 20 May 2013 09:19
Last modified: 14 Mar 2024 13:54

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Contributors

Author: Ashis Bhattacharjee
Author: Madhusudan Roy
Author: Vadim Ksenofontov
Author: Jonathan A. Kitchen ORCID iD
Author: Sally Brooker
Author: Philipp Gütlich

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