Calculated isotropic and anisotropic hyperfine coupling constants of transition metal ions

Ba, Goodman; Raynor, J. B.

doi:10.1016/0022-1902(70)80234-2

Cited by 27 publications

(3 citation statements)

References 2 publications

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“…The inverse operation of the observed anisotropic g tensor according to eq () results in the fact that the g Cu tensor has the elements of ( g Cu, x , g Cu, y , g Cu, z ) = (2.04, 2.01, 2.22). It is noteworthy that the estimated g tensor elements are small, compared with the theoretical g Cu, z value (∼2.6) that is calculated using the unit spin density on Cu, Δ 0 of 1 × 10 4 cm −1 estimated from the observed dd absorption of Cu−bisimpy and λ Cu of 829 cm −1 determined spectroscopically. , Because the covalent bonding effect tends to occur in Cu complexes coordinated with nitrogens, it is reasonable that the small g Cu anisotropy in Cu−bisimpy is discussed on the basis of the delocalization of Cu spin due to the covalent bonding effect. In order to estimate the σ bonding character between the d x 2 − y 2 and the ligand orbital (ϕ L ) in a square plane, therefore, we use a symmetry-adapted combination of nonbonding orbitals ( n ) belonging to three nitrogen atoms in the bisimpy ligand as shown in Figure .Two σ bonds (Ψ b and Ψ a ) are described by the bonding and antibonding combination between the d x 2 − y 2 and ϕ L orbitals using the normalization coefficients of c .…”

Section: Discussionmentioning

confidence: 85%

Peculiarity in the Electronic Structure of Cu(II) Complex Ferromagnetically Coupled with Bisimino Nitroxides

et al. 2008

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By means of the electron spin resonance (ESR) technique, we have investigated the electronic structures of the tridentate imino nitroxyl diradical complex with copper(II) (Cu−bisimpy), which has a square planar structure and a ground quartet state with an extremely strong ferromagnetic exchange interaction, and its related compounds (bisimpy = 2,6-bis(1′-oxyl-4′,4′,5′,5′-tetramethyl-4′,5′-dihydro-1′H-imidazol-2′-yl)pyridine). It was clarified that Cu−bisimpy had unique magnetic orbitals, compared with the biradical ligand (bisimpy), a zinc(II) biradical complex (Zn−bisimpy) and a copper(II) terpyridine complex (Cu−tpy) (tpy = 2,2′;6′,2′′-terpyridine). Multifrequency ESR spectroscopy provided a reliable set of magnetic parameters of Cu−bisimpy, which has a small g anisotropy (g x = 2.02, g y = 2.01, g z = 2.08) and small hyperfine coupling with Cu (|A x | = 42.0 MHz, |A y | ≤ 14 MHz, |A z | = 153 MHz) but huge zero-field splitting (D = +17.4 GHz, E = −1.0 GHz). The maximum principal axis of zero-field interaction (z ZF) is perpendicular to the z axis for the g and A tensors, which is normal to the molecular plane. These characteristics of the magnetic properties prove that the substantial spin transfer from the d x 2 −y 2 orbital of copper to the n-orbitals of the ligand is caused by a σ-type covalent bonding effect between the central metal and the ligand nitrogens. The covalent bonding effect produces carbene configurations on the nitrogen atoms of the imino nitroxyl radicals. The carbene configuration was concluded to be the main reason for the strong ferromagnetic coupling in Cu−bisimpy. Multifrequency electron spin resonance spectroscopy clarified the unique electronic structure of a square planar copper(II) complex with an imino nitroxyl diradical, which undergoes a strong ferromagnetic interaction caused by a covalent bonding effect.

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Section: Discussionmentioning

confidence: 85%

Peculiarity in the Electronic Structure of Cu(II) Complex Ferromagnetically Coupled with Bisimino Nitroxides

et al. 2008

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“…-351 I than on the molybdenum, especially when one allows for the smaller inherent couplings expected for 57Fe (Goodman & Raynor, 1970). As argued by Venters et al (1986), this might support an even formal oxidation state of molybdenum [e.g.…”

Section: Vol 262mentioning

confidence: 93%

E.p.r.-spectroscopic studies on the molybdenum–iron site of nitrogenase from Clostridium pasteurianum

George

Bare

et al. 1989

Biochemical Journal

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The e.p.r. spectroscopy of the nitrogenase molybdenum-iron protein from Clostridium pasteurianum was re-investigated. The sharpness of the delta Ms = +/- 3 g'z peak from the +/- 3/2 Kramer's doublet enables the observation and quantification of incompletely resolved hyperfine splittings from the stable magnetic nuclei 95Mo and 57Fe in samples enriched in these isotopes. No couplings to 1H or 17O could be discerned by examination of spectra from samples exchanged into 2H2O and H2(17)O respectively. Simulation of the spectrum from 95Mo-enriched samples yields a hyperfine coupling of 2.9 MHz, and indicates that the earlier electron-nuclear-double-resonance-derived estimate of 8.1 +/- 0.2 MHz is substantially in error.

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“…The correlation between the isotropic EPR parameters (g iso = 1.966; A iso = 109.8 G) agrees well with other reports for vanadyl complexes with O-donor ligands. 27,28 The anisotropic eightline spectrum at 77 K is resolved in parallel and perpendicular components (g || = 1.936; g ⊥ = 1.977; A || = 196.5 G; A ⊥ = 72.4 G), but the features associated with the (2) showing thermal ellipsoids drawn at 20% probability. J. Braz.…”

Section: Productmentioning

confidence: 99%

New titanium(IV) and vanadium(IV) haloalkoxides: synthetic route and structural characterisation

Nunes¹,

Reis²,

Camargo³

et al. 2003

J. Braz. Chem. Soc.

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Calculated isotropic and anisotropic hyperfine coupling constants of transition metal ions

Cited by 27 publications

References 2 publications

Peculiarity in the Electronic Structure of Cu(II) Complex Ferromagnetically Coupled with Bisimino Nitroxides

Peculiarity in the Electronic Structure of Cu(II) Complex Ferromagnetically Coupled with Bisimino Nitroxides

E.p.r.-spectroscopic studies on the molybdenum–iron site of nitrogenase from Clostridium pasteurianum

New titanium(IV) and vanadium(IV) haloalkoxides: synthetic route and structural characterisation

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