Halogen Substitution Effects on N2O Schiff Base Ligands in Unprecedented Abrupt FeII Spin Crossover Complexes

Wasinee Phonsri, David S Macedo, Kuduva R. Vignesh, Gopalan Rajaraman, Casey G. Davies, Guy N L Jameson, Boujemaa Moubaraki, Jas S. Ward, Paul E Kruger, Guillaume Chastanet, Keith S Murray

Research output: Contribution to journalArticleResearchpeer-review

Abstract

A family of halogen-substituted Schiff base iron(II) complexes, [FeII(qsal-X)2], (qsal-X=5-X-N-(8-quinolyl)salicylaldimines)) in which X=F (1), Cl (2), Br (3) or I (4) has been investigated in detail. Compound 1 shows a temperature invariant high spin state, whereas the others all show abrupt spin transitions, at or above room temperature, namely, 295 K (X=I) up to 342 K (X=Br), these being some of the highest T1/2 values obtained, to date, for FeII N/O species. We have recently reported subtle symmetry breaking in [FeII(qsal-Cl)2] 2 with two spin transition steps occurring at 308 and 316 K. A photomagnetic study reveals almost full HS conversion of [FeII(qsal-I)2] 4 at low temperature (T(LIESST)=54 °K). The halogen substitution effects on the magnetic properties, as well as the crystal packing of the [FeII(qsal-X)2] compounds and theoretical calculations, are discussed in depth, giving important knowledge for the design of new spin crossover materials. In comparison to the well known iron(III) analogues, [FeIII(qsal-X)2]+, the two extra π–π and P4AE interactions found in [FeII(qsal-X)2] compounds, are believed to be accountable for the spin transitions occurring at ambient temperatures.

Original languageEnglish
Pages (from-to)7052-7065
Number of pages14
JournalChemistry - A European Journal
Volume23
Issue number29
DOIs
Publication statusPublished - 2017

Keywords

  • halogen bonding
  • intermolecular interactions
  • iron complexes
  • Schiff base ligands
  • spin crossover

Cite this

Phonsri, Wasinee ; Macedo, David S ; Vignesh, Kuduva R. ; Rajaraman, Gopalan ; Davies, Casey G. ; Jameson, Guy N L ; Moubaraki, Boujemaa ; Ward, Jas S. ; Kruger, Paul E ; Chastanet, Guillaume ; Murray, Keith S. / Halogen Substitution Effects on N2O Schiff Base Ligands in Unprecedented Abrupt FeII Spin Crossover Complexes. In: Chemistry - A European Journal. 2017 ; Vol. 23, No. 29. pp. 7052-7065.
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title = "Halogen Substitution Effects on N2O Schiff Base Ligands in Unprecedented Abrupt FeII Spin Crossover Complexes",
abstract = "A family of halogen-substituted Schiff base iron(II) complexes, [FeII(qsal-X)2], (qsal-X=5-X-N-(8-quinolyl)salicylaldimines)) in which X=F (1), Cl (2), Br (3) or I (4) has been investigated in detail. Compound 1 shows a temperature invariant high spin state, whereas the others all show abrupt spin transitions, at or above room temperature, namely, 295 K (X=I) up to 342 K (X=Br), these being some of the highest T1/2 values obtained, to date, for FeII N/O species. We have recently reported subtle symmetry breaking in [FeII(qsal-Cl)2] 2 with two spin transition steps occurring at 308 and 316 K. A photomagnetic study reveals almost full HS conversion of [FeII(qsal-I)2] 4 at low temperature (T(LIESST)=54 °K). The halogen substitution effects on the magnetic properties, as well as the crystal packing of the [FeII(qsal-X)2] compounds and theoretical calculations, are discussed in depth, giving important knowledge for the design of new spin crossover materials. In comparison to the well known iron(III) analogues, [FeIII(qsal-X)2]+, the two extra π–π and P4AE interactions found in [FeII(qsal-X)2] compounds, are believed to be accountable for the spin transitions occurring at ambient temperatures.",
keywords = "halogen bonding, intermolecular interactions, iron complexes, Schiff base ligands, spin crossover",
author = "Wasinee Phonsri and Macedo, {David S} and Vignesh, {Kuduva R.} and Gopalan Rajaraman and Davies, {Casey G.} and Jameson, {Guy N L} and Boujemaa Moubaraki and Ward, {Jas S.} and Kruger, {Paul E} and Guillaume Chastanet and Murray, {Keith S}",
year = "2017",
doi = "10.1002/chem.201700232",
language = "English",
volume = "23",
pages = "7052--7065",
journal = "Chemistry - A European Journal",
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Phonsri, W, Macedo, DS, Vignesh, KR, Rajaraman, G, Davies, CG, Jameson, GNL, Moubaraki, B, Ward, JS, Kruger, PE, Chastanet, G & Murray, KS 2017, 'Halogen Substitution Effects on N2O Schiff Base Ligands in Unprecedented Abrupt FeII Spin Crossover Complexes' Chemistry - A European Journal, vol. 23, no. 29, pp. 7052-7065. https://doi.org/10.1002/chem.201700232

Halogen Substitution Effects on N2O Schiff Base Ligands in Unprecedented Abrupt FeII Spin Crossover Complexes. / Phonsri, Wasinee; Macedo, David S; Vignesh, Kuduva R.; Rajaraman, Gopalan; Davies, Casey G.; Jameson, Guy N L; Moubaraki, Boujemaa; Ward, Jas S.; Kruger, Paul E; Chastanet, Guillaume; Murray, Keith S.

In: Chemistry - A European Journal, Vol. 23, No. 29, 2017, p. 7052-7065.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Halogen Substitution Effects on N2O Schiff Base Ligands in Unprecedented Abrupt FeII Spin Crossover Complexes

AU - Phonsri, Wasinee

AU - Macedo, David S

AU - Vignesh, Kuduva R.

AU - Rajaraman, Gopalan

AU - Davies, Casey G.

AU - Jameson, Guy N L

AU - Moubaraki, Boujemaa

AU - Ward, Jas S.

AU - Kruger, Paul E

AU - Chastanet, Guillaume

AU - Murray, Keith S

PY - 2017

Y1 - 2017

N2 - A family of halogen-substituted Schiff base iron(II) complexes, [FeII(qsal-X)2], (qsal-X=5-X-N-(8-quinolyl)salicylaldimines)) in which X=F (1), Cl (2), Br (3) or I (4) has been investigated in detail. Compound 1 shows a temperature invariant high spin state, whereas the others all show abrupt spin transitions, at or above room temperature, namely, 295 K (X=I) up to 342 K (X=Br), these being some of the highest T1/2 values obtained, to date, for FeII N/O species. We have recently reported subtle symmetry breaking in [FeII(qsal-Cl)2] 2 with two spin transition steps occurring at 308 and 316 K. A photomagnetic study reveals almost full HS conversion of [FeII(qsal-I)2] 4 at low temperature (T(LIESST)=54 °K). The halogen substitution effects on the magnetic properties, as well as the crystal packing of the [FeII(qsal-X)2] compounds and theoretical calculations, are discussed in depth, giving important knowledge for the design of new spin crossover materials. In comparison to the well known iron(III) analogues, [FeIII(qsal-X)2]+, the two extra π–π and P4AE interactions found in [FeII(qsal-X)2] compounds, are believed to be accountable for the spin transitions occurring at ambient temperatures.

AB - A family of halogen-substituted Schiff base iron(II) complexes, [FeII(qsal-X)2], (qsal-X=5-X-N-(8-quinolyl)salicylaldimines)) in which X=F (1), Cl (2), Br (3) or I (4) has been investigated in detail. Compound 1 shows a temperature invariant high spin state, whereas the others all show abrupt spin transitions, at or above room temperature, namely, 295 K (X=I) up to 342 K (X=Br), these being some of the highest T1/2 values obtained, to date, for FeII N/O species. We have recently reported subtle symmetry breaking in [FeII(qsal-Cl)2] 2 with two spin transition steps occurring at 308 and 316 K. A photomagnetic study reveals almost full HS conversion of [FeII(qsal-I)2] 4 at low temperature (T(LIESST)=54 °K). The halogen substitution effects on the magnetic properties, as well as the crystal packing of the [FeII(qsal-X)2] compounds and theoretical calculations, are discussed in depth, giving important knowledge for the design of new spin crossover materials. In comparison to the well known iron(III) analogues, [FeIII(qsal-X)2]+, the two extra π–π and P4AE interactions found in [FeII(qsal-X)2] compounds, are believed to be accountable for the spin transitions occurring at ambient temperatures.

KW - halogen bonding

KW - intermolecular interactions

KW - iron complexes

KW - Schiff base ligands

KW - spin crossover

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