Details
| Original language | English |
|---|---|
| Pages (from-to) | 47-55 |
| Number of pages | 9 |
| Journal | POLYHEDRON |
| Volume | 16 |
| Issue number | 1 |
| Publication status | Published - 1997 |
Abstract
The magnetic properties of a hexacoordinated iron(II) complex with the bidentate ligand pyridylbenzimidazole (pybzim), [Fe(pybzim)3](ClO4)2·H2O, (1), have been investigated by AC susceptometry, 57Fe-Mössbauer, ESR and NMR spectroscopy. The temperature dependence of the AC magnetic susceptibility for a powder sample showed essentially diamagnetic behaviour below 85 K and paramagnetism (μeff/μB = 4.5-5.3, 5 = 2) above 160 K, obeying the Curie-Weiss law. Spin crossover behaviour can be found within the temperature range 90-160 K; it is centered at 141 K. The Mössbauer spectra confirm the susceptibility measurements: the area fraction of the high-spin quadrupole doublet plotted against temperature shows a curve similar to that deduced from susceptibility measurements. The complex is ESR silent in the X-band mode: neither the powder sample (77 K and 300 K) nor a methanolic solution exhibit an ESR signal. NMR measurements in methanol, acetone, nitromethane, acetonitrile and dimethylsulfoxide show an increasing magnetic moment μeff/μB from 1.6 (220 K, acetone) to 5.2 (325 K, DMSO), respectively. The spin-crossover transition of a freshly prepared powder sample is complete. However, time evolution causes (within months) an increasing admixture of iron(III), which was proved by magnetic susceptibility measurement, 57Fe-Mössbauer, ESR and electronic spectra of the complex.
Keywords
- ESR spectra, Iron(II), Magnetic susceptibility, Mössbauer spectra, NMR spectra, Spin-crossover
ASJC Scopus subject areas
- Chemistry(all)
- Physical and Theoretical Chemistry
- Chemistry(all)
- Inorganic Chemistry
- Materials Science(all)
- Materials Chemistry
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In: POLYHEDRON, Vol. 16, No. 1, 1997, p. 47-55.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Complete spin crossover in tris(pyridylbenzimidazole) iron(II)
AU - Boča, Roman
AU - Baran, Peter
AU - Dlháň, L'ubor
AU - Šima, Jozef
AU - Wiesinger, Günther
AU - Renz, Franz
AU - El-Ayaan, Usama
AU - Linert, Wolfgang
PY - 1997
Y1 - 1997
N2 - The magnetic properties of a hexacoordinated iron(II) complex with the bidentate ligand pyridylbenzimidazole (pybzim), [Fe(pybzim)3](ClO4)2·H2O, (1), have been investigated by AC susceptometry, 57Fe-Mössbauer, ESR and NMR spectroscopy. The temperature dependence of the AC magnetic susceptibility for a powder sample showed essentially diamagnetic behaviour below 85 K and paramagnetism (μeff/μB = 4.5-5.3, 5 = 2) above 160 K, obeying the Curie-Weiss law. Spin crossover behaviour can be found within the temperature range 90-160 K; it is centered at 141 K. The Mössbauer spectra confirm the susceptibility measurements: the area fraction of the high-spin quadrupole doublet plotted against temperature shows a curve similar to that deduced from susceptibility measurements. The complex is ESR silent in the X-band mode: neither the powder sample (77 K and 300 K) nor a methanolic solution exhibit an ESR signal. NMR measurements in methanol, acetone, nitromethane, acetonitrile and dimethylsulfoxide show an increasing magnetic moment μeff/μB from 1.6 (220 K, acetone) to 5.2 (325 K, DMSO), respectively. The spin-crossover transition of a freshly prepared powder sample is complete. However, time evolution causes (within months) an increasing admixture of iron(III), which was proved by magnetic susceptibility measurement, 57Fe-Mössbauer, ESR and electronic spectra of the complex.
AB - The magnetic properties of a hexacoordinated iron(II) complex with the bidentate ligand pyridylbenzimidazole (pybzim), [Fe(pybzim)3](ClO4)2·H2O, (1), have been investigated by AC susceptometry, 57Fe-Mössbauer, ESR and NMR spectroscopy. The temperature dependence of the AC magnetic susceptibility for a powder sample showed essentially diamagnetic behaviour below 85 K and paramagnetism (μeff/μB = 4.5-5.3, 5 = 2) above 160 K, obeying the Curie-Weiss law. Spin crossover behaviour can be found within the temperature range 90-160 K; it is centered at 141 K. The Mössbauer spectra confirm the susceptibility measurements: the area fraction of the high-spin quadrupole doublet plotted against temperature shows a curve similar to that deduced from susceptibility measurements. The complex is ESR silent in the X-band mode: neither the powder sample (77 K and 300 K) nor a methanolic solution exhibit an ESR signal. NMR measurements in methanol, acetone, nitromethane, acetonitrile and dimethylsulfoxide show an increasing magnetic moment μeff/μB from 1.6 (220 K, acetone) to 5.2 (325 K, DMSO), respectively. The spin-crossover transition of a freshly prepared powder sample is complete. However, time evolution causes (within months) an increasing admixture of iron(III), which was proved by magnetic susceptibility measurement, 57Fe-Mössbauer, ESR and electronic spectra of the complex.
KW - ESR spectra
KW - Iron(II)
KW - Magnetic susceptibility
KW - Mössbauer spectra
KW - NMR spectra
KW - Spin-crossover
UR - http://www.scopus.com/inward/record.url?scp=0039923937&partnerID=8YFLogxK
U2 - 10.1016/0277-5387(96)00255-0
DO - 10.1016/0277-5387(96)00255-0
M3 - Article
AN - SCOPUS:0039923937
VL - 16
SP - 47
EP - 55
JO - POLYHEDRON
JF - POLYHEDRON
SN - 0277-5387
IS - 1
ER -