Some aspects of the electron paramagnetic resonance spectroscopy of d-transition metal compounds

Mabbs, Frank E.

doi:10.1039/cs9932200313

Cited by 115 publications

(102 citation statements)

References 11 publications

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“…The calculated parameters for 1 and the parameters obtained from simulations of 6 differ, chiefly in the magnitude of D (ab initio: +4.4/+3.2 cm −1 ; experimental: +1.6/+1.1 cm −1 ). The observed axiality of g is reproduced, and is of the same sense (gz < gx = gy), which is consistent with a positive D. 32,33 What is most noticeable about the calculated parameters is the extreme sensitivity of D to the nickel coordination environment. This parameter varies from +8.7 to −3.0 cm −1 with only minor changes in coordination sphere.…”

Section: Single Ion Anisotropy: Computational Modelingsupporting

confidence: 69%

On the Possibility of Magneto-Structural Correlations: Detailed Studies of Dinickel Carboxylate Complexes

Walsh

Sproules

Chilton³

et al. 2014

Inorg. Chem.

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Bu, L = HO 2 C t Bu (1), pyridine (2), 3-methylpyridine (4); L = L = pyridine (3), 3-methylpyridine (5)) has been synthesized and structurally characterized by X-ray crystallography. The magnetic properties have been probed by magnetometry and EPR spectroscopy, and detailed measurements show that the axial zero-field splitting, D, of the nickel( ) ions is on the same order as the isotropic exchange interaction, J, between the nickel sites. The isotropic exchange interaction can be related to the angle between the nickel centers and the bridging water molecule, while the magnitude of D can be related to the coordination sphere at the nickel sites.

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Section: Single Ion Anisotropy: Computational Modelingsupporting

confidence: 69%

On the Possibility of Magneto-Structural Correlations: Detailed Studies of Dinickel Carboxylate Complexes

Walsh

Sproules

Chilton³

et al. 2014

Inorg. Chem.

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“…ESR simulations were performed by simulation programs developed by Mabbs and Collison. 18,19 ESR intensities of the as-synthesized and calcined samples were obtained by double integration of the ESR spectra obtained under nonsaturating conditions. The whole magnetic field sweep range was integrated for X-band spectra, whereas only the "g ⊥ " was used for integration of the Q-band spectra.…”

Section: Methodsmentioning

confidence: 99%

“…19 An example of a simulated spectrum is shown in Figure 4 for as-synthesized CoAPO-5 with 0.05 Co. The spin Hamiltonian parameters obtained are given in Table 3.…”

Section: Esr Signals Of Comentioning

confidence: 99%

Electron Spin Resonance of High-Spin Cobalt in Microporous Crystalline Cobalt-Containing Aluminophosphates

et al. 1999

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Four highly crystalline, cobalt-containing microporous aluminophosphates have been investigated by using liquid He X-and/or Q-band electron spin resonance (ESR) spectroscopy in order to investigate the coordination of high-spin cobalt before and after calcination. The ESR spectra of the four zeolite structures are characterized by an axial signal with an effective g ⊥ ≈ 5.80-5.44 and g || ≈ 2.00. Quantitative temperature dependence measurements of this axial signal in the temperature range 4-30 K reveal a Curie-Weiss behavior for both as-synthesized and calcined samples confirming (a) the m s ) ( 1/2 ground state of magnetically isolated high-spin cobalt and (b) a zero field splitting ∆ > 0 cm -1 . Quantitation of the ESR signals indicated that most of the Co 2+ is ESR active and that only about 30% of this Co 2+ can be oxidized to the ESR-inactive Co 3+ after calcination. The spin Hamiltonian parameters of as-synthesized and calcined CoAPO-5 material, as determined by spectrum simulation and the microwave power saturation technique, support the presence of framework Co 2+ in a flattened or elongated tetrahedron (D 2d ).

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“…Accordingly, Fe 3+ can give rise to a large variety of resonances over a wide range of effective g-values. 63 The signal at g eff = 4.1 is as- Figure 8 shows spectra of 0.26FeZc before (Figure 8a) and after digestion at different temperatures (Figure 8b, 8c). Treatment at 673 K (Figure 8b) did not visibly change the spectrum, i.e.…”

Section: Electron Paramagnetic Resonancementioning

confidence: 99%

Incorporation of manganese and iron into the zirconia lattice in promoted sulfated zirconia catalysts

Jentoft

Hahn

Kröhnert

et al. 2004

Journal of Catalysis

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Two series of Mn-or Fe-promoted zirconia samples were prepared, (i) a series of sulfated-free reference compounds via co-precipitation of aqueous solutions containing zirconium and the promoter cation, and (ii) a series of catalysts via incipient-wetness impregnation of a sulfated zirconium hydroxide. The promoter content was varied between 0 and 5 wt% metal. All promoter-containing materials were calcined at 923 K. The reference materials contained mainly isolated Mn or Fe species incorporated into the zirconia lattice as evidenced by stabilization of the tetragonal zirconia phase, EPR (isolated ions in highly symmetric environment), and a shrinking unit cell volume (XRD) of the tetragonal zirconia phase with increasing promoter content. Only the Mn-promoted catalysts showed such shrinkage in unit cell volume with increasing promoter content. At 2 wt% promoter content, Fe could, and Mn could not be detected by ion scattering spectroscopy on the surface of the catalysts. The Fepromoted catalysts contained Fe2O3-like surface species (EPR, XANES), which could at least in part be removed by washing with oxalic acid. Catalysts were tested for isomerization at 338 K using 1 kPa n-butane in balance of N2. At 0.5 wt% promoter content the maximum rates produced by the 0.5 wt% Mn-promoted and Fe-promoted sulfated zirconia were about 80 and 20 µmol g -1 h -1 , respectively. Mn was thus more effective as a promoter for n-butane isomerization than Fe, despite the more extensive incorporation into the zirconia lattice.

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Some aspects of the electron paramagnetic resonance spectroscopy of d-transition metal compounds

Abstract: A g,, f gVv f g,, All coincident A x , # A , # A,, gxx + g y y # g,, One axis ofg and gxx # g,, # gz, Complete gxx = g y y # g,, Only g,, and A,,

Cited by 115 publications

References 11 publications

On the Possibility of Magneto-Structural Correlations: Detailed Studies of Dinickel Carboxylate Complexes

On the Possibility of Magneto-Structural Correlations: Detailed Studies of Dinickel Carboxylate Complexes

Electron Spin Resonance of High-Spin Cobalt in Microporous Crystalline Cobalt-Containing Aluminophosphates

Incorporation of manganese and iron into the zirconia lattice in promoted sulfated zirconia catalysts

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