Hysteretic thermal spin-crossover and symmetry breaking in heteroleptic Fe(II) complexes using alkyl chain substituted 2,2’-dipyridylamine ligands.
Hysteretic thermal spin-crossover and symmetry breaking in heteroleptic Fe(II) complexes using alkyl chain substituted 2,2’-dipyridylamine ligands.
The alkyl chain carrying ligands N,N-di(pyridin-2-yl)butanamide (LC4) and N,N-di(pyridin-2-yl)decanamide (LC10) were combined with NCS− co-ligands to form the neutral heteroleptic Fe(II) complexes trans-[FeII(LC4)2(NCS)2] (1C4) and trans-[FeII(LC10)2(NCS)2] (1C10). Variable temperature crystallographic studies revealed that 1C4 is in the orthorhombic space group Pna21 between 85–200 K whereas 1C10 is in the monoclinic space group P21/c between 85–140 K. The average Fe–N bond lengths suggest that at 85 K 1C4 contains LS Fe(II) centres; however, the ca. 0.18 Å increase in the average Fe–N bond lengths between 85 and 120 K suggests a spin-transition to the HS state occurs within this temperature interval. 1C10 contains LS Fe(II) centres between 85 and 105 K. Upon warming from 105 to 140 K the average Fe–N bond lengths increase by ca. 0.19 Å, which suggests a spin-transition to the HS state. Solid-state magnetic susceptibility measurements showed that 1C4 undergoes semi-abrupt spin-crossover with T1/2 = 127.5 K and a thermal hysteresis of ca. 13 K whereas, 1C10 undergoes an abrupt spin-crossover with T1/2 = 119.0 K, and is also accompanied by thermal hysteresis of ca. 4 K. The crystallographic and magnetic data show that the length of the complex's alkyl chain substituents can have a large impact on the structure of the crystal lattice as well as a subtle effect on the T1/2 value for thermal spin-crossover.
17340-17348
Geoghegan, Blaise L.
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Phonsri, Wasinee
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Horton, Peter
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Orton, James
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Coles, Simon J.
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Murray, Keith S.
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Cragg, Peter J.
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Dymond, Marcus K
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Gass, Ian A.
426dea92-36c7-4c15-be57-22b4c1a19865
14 December 2019
Geoghegan, Blaise L.
f92c23d3-84b2-4a37-b5c4-45887ae565a9
Phonsri, Wasinee
dfd62f21-6354-4404-982e-5eea2af651c5
Horton, Peter
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Orton, James
4e2a471f-9e11-4cb4-abb6-d0398047939f
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Murray, Keith S.
091a4624-9b14-4413-923b-7330444e64b2
Cragg, Peter J.
41d46d0a-4553-471e-af42-dccf3fa403e9
Dymond, Marcus K
0deb02c8-4dec-418b-94ec-98594ed597b7
Gass, Ian A.
426dea92-36c7-4c15-be57-22b4c1a19865
Geoghegan, Blaise L., Phonsri, Wasinee, Horton, Peter, Orton, James, Coles, Simon J., Murray, Keith S., Cragg, Peter J., Dymond, Marcus K and Gass, Ian A.
(2019)
Hysteretic thermal spin-crossover and symmetry breaking in heteroleptic Fe(II) complexes using alkyl chain substituted 2,2’-dipyridylamine ligands.
Dalton Transactions, 48 (46), .
(doi:10.1039/C9DT03412A).
Abstract
The alkyl chain carrying ligands N,N-di(pyridin-2-yl)butanamide (LC4) and N,N-di(pyridin-2-yl)decanamide (LC10) were combined with NCS− co-ligands to form the neutral heteroleptic Fe(II) complexes trans-[FeII(LC4)2(NCS)2] (1C4) and trans-[FeII(LC10)2(NCS)2] (1C10). Variable temperature crystallographic studies revealed that 1C4 is in the orthorhombic space group Pna21 between 85–200 K whereas 1C10 is in the monoclinic space group P21/c between 85–140 K. The average Fe–N bond lengths suggest that at 85 K 1C4 contains LS Fe(II) centres; however, the ca. 0.18 Å increase in the average Fe–N bond lengths between 85 and 120 K suggests a spin-transition to the HS state occurs within this temperature interval. 1C10 contains LS Fe(II) centres between 85 and 105 K. Upon warming from 105 to 140 K the average Fe–N bond lengths increase by ca. 0.19 Å, which suggests a spin-transition to the HS state. Solid-state magnetic susceptibility measurements showed that 1C4 undergoes semi-abrupt spin-crossover with T1/2 = 127.5 K and a thermal hysteresis of ca. 13 K whereas, 1C10 undergoes an abrupt spin-crossover with T1/2 = 119.0 K, and is also accompanied by thermal hysteresis of ca. 4 K. The crystallographic and magnetic data show that the length of the complex's alkyl chain substituents can have a large impact on the structure of the crystal lattice as well as a subtle effect on the T1/2 value for thermal spin-crossover.
Text
Fe(dpa-Cn)2(NCS)2 SCO
- Accepted Manuscript
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Accepted/In Press date: 10 November 2019
e-pub ahead of print date: 15 November 2019
Published date: 14 December 2019
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Local EPrints ID: 436607
URI: http://eprints.soton.ac.uk/id/eprint/436607
ISSN: 0300-9246
PURE UUID: 64d4fd9e-a31a-4d26-b11a-98b29592c6a8
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Date deposited: 18 Dec 2019 17:30
Last modified: 17 Mar 2024 05:08
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Author:
Blaise L. Geoghegan
Author:
Wasinee Phonsri
Author:
Peter Horton
Author:
James Orton
Author:
Keith S. Murray
Author:
Peter J. Cragg
Author:
Marcus K Dymond
Author:
Ian A. Gass
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