The angular overlap model for the description of the paramagnetic properties of transition metal complexes

The compound [Co(hfac)2-(NITPhOMe)2] (2) (hfac = hexafluoroacetylacetonate, NITPhOMe = 4'-methoxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) crystallizes in the triclinic P1 space group, a= 10.870(5), b = 11.520(5), c = 19.749(5) A, alpha = 78.05(5), beta = 84.20(5), gamma = 64.51(5) degrees, Z = 2. It can be considered a model system for studying the nature of the magnetic anisotropy of [Co(hfac)2(NITPhOMe)] (1), which was recently reported to behave as a molecular magnetic wire. The magnetic anisotropy of 2 was investigated by EPR spectroscopy and SQUID magnetometry both in the polycrystalline powder and in a single crystal. The experimental magnetic anisotropy was related to the anisotropy of the central ion and to the exchange interaction between the cobalt(II) ion and the radicals.

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“…This was later generalized by the Florence group who used the ligand-field model. [19,20] At the Ising limit, g z 8 ± 9, g x g y 0.…”

Section: Discussionmentioning

confidence: 99%

Ising-Type Magnetic Anisotropy in a Cobalt(II) Nitronyl Nitroxide Compound: A Key to Understanding the Formation of Molecular Magnetic Nanowires

et al. 2002

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“…Moreover, it is possible to use the real coordination geometry around the metal ion site, thus including e!ects due to the low symmetry of the ligand "eld (29). This was applied in the past to the rationalization of spectroscopic, magnetic, and EPR properties of complexes containing Kramers ions such as Cu'' and Co'' in low-symmetry environments (30,31).…”

Section: Sample Calculation Of Single-ion Anisotropy Through the Angumentioning

confidence: 98%

Hints for the Control of Magnetic Anisotropy in Molecular Materials

Gatteschi

Sorace

2001

Journal of Solid State Chemistry

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129

105

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“…[11][12][13] This is a necessary first step for checking whether the experimental data can be reproduced by calculations and to validate the AOM parameters chosen. The calculations for 1 and 2 led to the following values:…”

Section: Angular Overlap Calculationsmentioning

confidence: 99%

Glycoligands Tuning the Magnetic Anisotropy of Ni^II Complexes

Charron

Bellot

Cisnetti

et al. 2007

Chemistry A European J

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Two organic ligands based on a sugar-scaffold derived from galactose and possessing three O-CH(2)-pyridine pendant arms at the 3-, 4-, and 5-positions of the galactopyranose that act as chelates afford mononuclear complexes when reacted with a Ni(II) salt. The magnetization behavior in the form of M=f(H/T) plots suggests the presence of appreciable magnetic anisotropy within the two complexes. The analysis of the EPR spectra performed at two different temperatures (7 and 17 K) and at three frequencies (190, 285, and 380 GHz) leads to the conclusion that the anisotropy has a high degree of axiality (E/D=0.17 for the two complexes), but with a different sign of the D parameter. The spin hamiltonian parameters D and E were reproduced for the two complexes by using calculations based on the angular overlap model (AOM). The structural difference between the two complexes responsible of the sign of the D parameters was also determined using AOM calculations. A thorough analysis of the structures showed that the structural differences in the coordination sphere of the two complexes responsible of the different D parameter sign result from the nature of the sugar scaffolds. In complex 1, the sugar scaffold imposes an intramolecular hydrogen bond with one of the atoms linked to Ni(II); this arrangement leads to a distorted coordination sphere and positive D value, while the absence of such a hydrogen bond in complex 2 leads to a less distorted environment around the Ni center and to a negative D value.

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The angular overlap model for the description of the paramagnetic properties of transition metal complexes

Cited by 73 publications

References 153 publications

Ising-Type Magnetic Anisotropy in a Cobalt(II) Nitronyl Nitroxide Compound: A Key to Understanding the Formation of Molecular Magnetic Nanowires

Ising-Type Magnetic Anisotropy in a Cobalt(II) Nitronyl Nitroxide Compound: A Key to Understanding the Formation of Molecular Magnetic Nanowires

Hints for the Control of Magnetic Anisotropy in Molecular Materials

Glycoligands Tuning the Magnetic Anisotropy of Ni^II Complexes

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The angular overlap model for the description of the paramagnetic properties of transition metal complexes

Cited by 73 publications

References 153 publications

Ising-Type Magnetic Anisotropy in a Cobalt(II) Nitronyl Nitroxide Compound: A Key to Understanding the Formation of Molecular Magnetic Nanowires

Ising-Type Magnetic Anisotropy in a Cobalt(II) Nitronyl Nitroxide Compound: A Key to Understanding the Formation of Molecular Magnetic Nanowires

Hints for the Control of Magnetic Anisotropy in Molecular Materials

Glycoligands Tuning the Magnetic Anisotropy of NiII Complexes

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Glycoligands Tuning the Magnetic Anisotropy of Ni^II Complexes