Direct Measurement of the Hyperfine and g-Tensors of a Mn(III)−Mn(IV) Complex in Polycrystalline and Frozen Solution Samples by High-Field EPR
| Autor: | Michèle Cesario, Sun Un, Geneviève Blondin, Christelle Hureau |
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| Rok vydání: | 2003 |
| Předmět: |
Analytical chemistry
Biochemistry Catalysis law.invention chemistry.chemical_compound Colloid and Surface Chemistry Nuclear magnetic resonance Biomimetic Materials law Freezing Organometallic Compounds Electron paramagnetic resonance Acetonitrile Anisotropy Hyperfine structure Manganese Valence (chemistry) Electron Spin Resonance Spectroscopy Matrix isolation Photosystem II Protein Complex General Chemistry Catalase Ethylenediamines Magnetic susceptibility Models Chemical chemistry Crystallization Ground state |
| Zdroj: | Journal of the American Chemical Society. 125:11637-11645 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja035153b |
| Popis: | The g-tensors and hyperfine tensors of the S = (1)/(2) ground state of the mixed valence [LMn(IIImu-O)(2)Mn(IV)L](3+) complex (L = N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2-diamine) was deter-mined in the solid-state and frozen acetonitrile solution by high-field EPR. Both samples exhibited complex anisotropic temperature behaviors that precluded the use of routine spectrum simulation procedures to extract the spin parameters. To circumvent this problem, the parameters were measured directly by using multifrequency techniques. In the case of the frozen solution, this approach yielded seven of the nine spin parameters with varying uncertainty, the two extreme principal g-values, the four hyperfine couplings associated with each of these two g-values, and the middle g-value. This latter parameter was obtained from a first moment analysis. Unlike simulations, the statistical errors associated with each value could be assigned in a straightforward and rigorous manner. The directly measured g-values were different in frozen solution and polycrystalline powder. The temperature dependence of the high-field EPR spectra of the polycrystalline powder revealed a spin-spin interaction between the neighboring binuclear complexes. |
| Databáze: | OpenAIRE |
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