Polymorphs of spin-crossover iron(II) complex fac-[FeII(HLn -Pr)3]Cl·PF6 (HLn -Pr=2-methylimidazol-4-yl-methylideneamino-n-propyl): Assembly structures and scan rate dependent spin-crossover properties with thermal hysteresis

Takahiro Ueno, Yuto Ii, Takeshi Fujinami, Naohide Matsumoto, Seiichiro Iijima, Yukinari Sunatsuki

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Abstract

Two polymorphs of iron(II) complex fac-[FeII(HL n -Pr)3]Cl·PF6, 1 and 2, were obtained (HL n -Pr =2-methylimidazole-4-yl-methylideneamino-n-propyl ligand). Complex cations, fac-[FeII(HL n -Pr)3]2+, of 1 and 2 had similar octahedral and facial geometries coordinated with three bidentate HL n -Pr ligands. The three imidazole groups in fac-[FeII(HL n -Pr)3]2+ with δ- and Λ-enantiomorphs are hydrogen-bonded with three Cl- ions, forming one-dimensional (1D) and two-dimensional (2D) network structures in 1 and 2, respectively. Complex 1 had a ladder-like 1D structure formed by imidazole⋯chloride hydrogen bonds, with a circular binuclear net unit of (⋯fac-[FeII(HL n -Pr)3]2+⋯Cl-⋯)2, and showed two successive scan rate dependent spin crossover (SCO) processes with thermal hysteresis. Complex 2 had a 2D network structure formed by imidazole⋯chloride hydrogen bonds with circular binuclear and tetranuclear net units of (⋯fac-[FeII(HL n -Pr)3]2+⋯Cl-⋯)2,4, and showed a one-step scan rate dependent SCO profile centered at 143K with thermal hysteresis. The relaxation property was identified from the scan rate dependence of magnetic susceptibility and temperature dependent Mössbauer spectra and X-ray diffraction studies. The crystal structure of 2 was analyzed at 12 temperatures in a cooling cycle. Upon lowering the temperature, the crystal system transformed from a monoclinic to a triclinic lattice at 210K in a high-spin state, and then transformed to a low-spin state at 150K in the triclinic system.

Original languageEnglish
JournalPolyhedron
DOIs
Publication statusAccepted/In press - Dec 1 2016

Fingerprint

Polymorphism
Hysteresis
crossovers
Iron
assembly
hysteresis
iron
Hydrogen bonds
Ligands
Ladders
hydrogen bonds
Magnetic susceptibility
Temperature
ligands
Cations
Hydrogen
enantiomers
Crystal structure
Positive ions
imidazoles

Keywords

  • 2D network structure
  • Bidentate ligand
  • Hydrogen bond
  • Iron(II) complex
  • Spin crossover

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

@article{77c39f69aeb74916959aaa0a7e159e28,
title = "Polymorphs of spin-crossover iron(II) complex fac-[FeII(HLn -Pr)3]Cl·PF6 (HLn -Pr=2-methylimidazol-4-yl-methylideneamino-n-propyl): Assembly structures and scan rate dependent spin-crossover properties with thermal hysteresis",
abstract = "Two polymorphs of iron(II) complex fac-[FeII(HL n -Pr)3]Cl·PF6, 1 and 2, were obtained (HL n -Pr =2-methylimidazole-4-yl-methylideneamino-n-propyl ligand). Complex cations, fac-[FeII(HL n -Pr)3]2+, of 1 and 2 had similar octahedral and facial geometries coordinated with three bidentate HL n -Pr ligands. The three imidazole groups in fac-[FeII(HL n -Pr)3]2+ with δ- and Λ-enantiomorphs are hydrogen-bonded with three Cl- ions, forming one-dimensional (1D) and two-dimensional (2D) network structures in 1 and 2, respectively. Complex 1 had a ladder-like 1D structure formed by imidazole⋯chloride hydrogen bonds, with a circular binuclear net unit of (⋯fac-[FeII(HL n -Pr)3]2+⋯Cl-⋯)2, and showed two successive scan rate dependent spin crossover (SCO) processes with thermal hysteresis. Complex 2 had a 2D network structure formed by imidazole⋯chloride hydrogen bonds with circular binuclear and tetranuclear net units of (⋯fac-[FeII(HL n -Pr)3]2+⋯Cl-⋯)2,4, and showed a one-step scan rate dependent SCO profile centered at 143K with thermal hysteresis. The relaxation property was identified from the scan rate dependence of magnetic susceptibility and temperature dependent M{\"o}ssbauer spectra and X-ray diffraction studies. The crystal structure of 2 was analyzed at 12 temperatures in a cooling cycle. Upon lowering the temperature, the crystal system transformed from a monoclinic to a triclinic lattice at 210K in a high-spin state, and then transformed to a low-spin state at 150K in the triclinic system.",
keywords = "2D network structure, Bidentate ligand, Hydrogen bond, Iron(II) complex, Spin crossover",
author = "Takahiro Ueno and Yuto Ii and Takeshi Fujinami and Naohide Matsumoto and Seiichiro Iijima and Yukinari Sunatsuki",
year = "2016",
month = "12",
day = "1",
doi = "10.1016/j.poly.2017.03.028",
language = "English",
journal = "Polyhedron",
issn = "0277-5387",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - Polymorphs of spin-crossover iron(II) complex fac-[FeII(HLn -Pr)3]Cl·PF6 (HLn -Pr=2-methylimidazol-4-yl-methylideneamino-n-propyl)

T2 - Assembly structures and scan rate dependent spin-crossover properties with thermal hysteresis

AU - Ueno, Takahiro

AU - Ii, Yuto

AU - Fujinami, Takeshi

AU - Matsumoto, Naohide

AU - Iijima, Seiichiro

AU - Sunatsuki, Yukinari

PY - 2016/12/1

Y1 - 2016/12/1

N2 - Two polymorphs of iron(II) complex fac-[FeII(HL n -Pr)3]Cl·PF6, 1 and 2, were obtained (HL n -Pr =2-methylimidazole-4-yl-methylideneamino-n-propyl ligand). Complex cations, fac-[FeII(HL n -Pr)3]2+, of 1 and 2 had similar octahedral and facial geometries coordinated with three bidentate HL n -Pr ligands. The three imidazole groups in fac-[FeII(HL n -Pr)3]2+ with δ- and Λ-enantiomorphs are hydrogen-bonded with three Cl- ions, forming one-dimensional (1D) and two-dimensional (2D) network structures in 1 and 2, respectively. Complex 1 had a ladder-like 1D structure formed by imidazole⋯chloride hydrogen bonds, with a circular binuclear net unit of (⋯fac-[FeII(HL n -Pr)3]2+⋯Cl-⋯)2, and showed two successive scan rate dependent spin crossover (SCO) processes with thermal hysteresis. Complex 2 had a 2D network structure formed by imidazole⋯chloride hydrogen bonds with circular binuclear and tetranuclear net units of (⋯fac-[FeII(HL n -Pr)3]2+⋯Cl-⋯)2,4, and showed a one-step scan rate dependent SCO profile centered at 143K with thermal hysteresis. The relaxation property was identified from the scan rate dependence of magnetic susceptibility and temperature dependent Mössbauer spectra and X-ray diffraction studies. The crystal structure of 2 was analyzed at 12 temperatures in a cooling cycle. Upon lowering the temperature, the crystal system transformed from a monoclinic to a triclinic lattice at 210K in a high-spin state, and then transformed to a low-spin state at 150K in the triclinic system.

AB - Two polymorphs of iron(II) complex fac-[FeII(HL n -Pr)3]Cl·PF6, 1 and 2, were obtained (HL n -Pr =2-methylimidazole-4-yl-methylideneamino-n-propyl ligand). Complex cations, fac-[FeII(HL n -Pr)3]2+, of 1 and 2 had similar octahedral and facial geometries coordinated with three bidentate HL n -Pr ligands. The three imidazole groups in fac-[FeII(HL n -Pr)3]2+ with δ- and Λ-enantiomorphs are hydrogen-bonded with three Cl- ions, forming one-dimensional (1D) and two-dimensional (2D) network structures in 1 and 2, respectively. Complex 1 had a ladder-like 1D structure formed by imidazole⋯chloride hydrogen bonds, with a circular binuclear net unit of (⋯fac-[FeII(HL n -Pr)3]2+⋯Cl-⋯)2, and showed two successive scan rate dependent spin crossover (SCO) processes with thermal hysteresis. Complex 2 had a 2D network structure formed by imidazole⋯chloride hydrogen bonds with circular binuclear and tetranuclear net units of (⋯fac-[FeII(HL n -Pr)3]2+⋯Cl-⋯)2,4, and showed a one-step scan rate dependent SCO profile centered at 143K with thermal hysteresis. The relaxation property was identified from the scan rate dependence of magnetic susceptibility and temperature dependent Mössbauer spectra and X-ray diffraction studies. The crystal structure of 2 was analyzed at 12 temperatures in a cooling cycle. Upon lowering the temperature, the crystal system transformed from a monoclinic to a triclinic lattice at 210K in a high-spin state, and then transformed to a low-spin state at 150K in the triclinic system.

KW - 2D network structure

KW - Bidentate ligand

KW - Hydrogen bond

KW - Iron(II) complex

KW - Spin crossover

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