A cautionary note on the use of the Evans method for magnetic moments

Ostfeld, David; Cohen, Ilan

doi:10.1021/ed049p829

Cited by 83 publications

(51 citation statements)

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“…In presence of spin orbit coupling, the degenerate spin states split into three Kramers doublets. The observed EPR spectrum depends on the ratio of D/E and the Zeeman quantum energy hν (ν is the operating frequency of the EPR spectrometer) . In high‐spin iron(III) complexes of cubic symmetry the resonance absorption occurs for D<hν (slight distortion) in the lowest‐energy (ground‐state) doublet and between separate doublets; the EPR spectrum can be described by an effective spin of 5/2 and the observed isotropic g factors are close to that of a free electron (g e =2.0023).…”

Section: Resultsmentioning

confidence: 99%

Effect of Ligand Field Strength on the Spin Crossover Behaviour in 5‐X‐SalEen (X=Me, Br and OMe) Based Fe(III) Complexes

Dey

Mondal

Konar

2020

Chemistry An Asian Journal

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The reaction of Fe(NCS) 3 prepared in situ in MeOH with 5-X-SalEen ligands (5-X-SalEen = condensation product of 5-substituted salicylaldehyde and N-ethylethylenediamine) provided three Fe(III) complexes, [Fe(5-X-SalEen) 2 ]NCS; X=Me (1), X=Br (2), X=OMe (3). All the complexes reveal similar structural features but a very different magnetic profile. Complex 1 shows a gradual spin crossover while complexes 2 and 3 show a sharp spin transition. The T 1/2 for complex 2 is 237 K while for complex 3 it is much higher with a value of 361 K. The spin transition temperature is shifted towards higher temperature with increasing electron-donation ability of the ligand substituents. This experimental observation has been rationalized with DFT calculations. UV-Vis and cyclic voltammetry studies support the fact that the electron density on the ligand increases from Me to Br to OMe substituents. To understand the change in spin states, temperature-dependent EPR spectra have been recorded. The spin state equilibrium in the liquid state has been probed with Evans NMR spectroscopic method, and thermodynamic parameters have been evaluated for all complexes.

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Section: Resultsmentioning

confidence: 99%

Effect of Ligand Field Strength on the Spin Crossover Behaviour in 5‐X‐SalEen (X=Me, Br and OMe) Based Fe(III) Complexes

Dey

Mondal

Konar

2020

Chemistry An Asian Journal

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“…The solvent density at the given temperature was factored in to the magnetic susceptibility calculation. 77,78 Cyclic voltammetry studies were carried out using a BASi Epsilon-EC potentiostat under computer control. iR drop was compensated by the feedback method.…”

Section: Discussionmentioning

confidence: 99%

A base-free synthetic route to anti-bimetallic lanthanide pentalene complexes

Kilpatrick

Cloke

2017

Dalton Trans.

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“…Magnetic moments were determined using Evan’s method in DMSO. ix Elemental analyses were performed on a Perkin-Elmer 2400 Series II CHNS analyzer.…”

Section: Methodsmentioning

confidence: 99%

Nickel(II) complexes stabilized by bis[N-(6-pivalamido-2-pyridylmethyl)]benzylamine: Synthesis and characterization of complexes stabilized by a hydrogen bonding network

Powell-Jia

Pham

Borovik

2010

Inorganica Chimica Acta

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Hydrogen bonds in metalloproteins are key in directing reactivity yet to be achieved in synthetic systems. We have been developing a synthetic system that uses hydrogen-bonding interactions to modulate the secondary coordination around a transition metal ion. This was accomplished with the ligand bis[N-(6-pivalamido-2-pyridylmethyl)]benzylamine (H2pmb), which contains two carboxyamido units appended from pyridine rings. Several nickel complexes were prepared and structurally characterized. In particular, we found that the appended carboxyamido groups either provide intramolecular H-bond donors or can be converted to bind directly to a metal center. We established that the complex NiIIH2pmb(Cl)2 can be sequentially deprotonated with potassium tert-butoxide, causing coordination of the carboxyamido oxygen atoms and concomitant loss of the chloro ligands. The chloro ligands were also removed with silver(I) salts—in the presence of acetate ions, the complex NiIIH2pmb(κ2-OAc)(κ1-OAc) was isolated, in which an intramolecular H-bonding network occurs between the H2pmb ligand and the coordinate acetato ligands.

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A cautionary note on the use of the Evans method for magnetic moments

Abstract: A great advantage of the Evans (1) nmr method for the determination of magnetic susceptibility is that measurements are made on the solution phase and thereby supplement the solid state measurements made by the Gouy and Faraday techniques.

Cited by 83 publications

References 1 publication

Effect of Ligand Field Strength on the Spin Crossover Behaviour in 5‐X‐SalEen (X=Me, Br and OMe) Based Fe(III) Complexes

Effect of Ligand Field Strength on the Spin Crossover Behaviour in 5‐X‐SalEen (X=Me, Br and OMe) Based Fe(III) Complexes

A base-free synthetic route to anti-bimetallic lanthanide pentalene complexes

Nickel(II) complexes stabilized by bis[N-(6-pivalamido-2-pyridylmethyl)]benzylamine: Synthesis and characterization of complexes stabilized by a hydrogen bonding network

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