ESR study of anion radicals produced in cathodic reduction of 2-furfural derivatives

Andrej Staško; Peter Pelikán; František Tomanovič; Viliam Pätoprstý

doi:10.1135/cccc19790762

ESR study of anion radicals produced in cathodic reduction of 2-furfural derivatives

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19790762 ◽

1979 ◽

Vol 44 (3) ◽

pp. 762-772 ◽

Cited By ~ 8

Author(s):

Andrej Staško ◽

Peter Pelikán ◽

František Tomanovič ◽

Viliam Pätoprstý

Keyword(s):

Nitrogen Atom ◽

Nitro Group ◽

Spin Density ◽

Unpaired Electron ◽

Indo Method ◽

Hammett Constants ◽

Half Wave ◽

The Individual ◽

Maximum Spin ◽

Anion Radicals

Furfural and its derivatives are reduced reversibly to the corresponding anion radicals during polarography in dimethylformamide. These radicals have been studied by ESR, and analysis of their spectra has been carried out. The calculated splitting constants and half-wave potentials (INDO method) agree well with the experiment. The maximum spin density of the unpaired electron has been found for the aldehydic proton of the furfural anion (aH = 1.01 mT), the values for the remaining protons of furane ring being smaller (aH3 = 0.115 mT, aH4 = 0.49 mT, and aH5 = 0.64 mT). Introduction of nitro group in 5 position of furfural results in a marked shift of spin density of the nitrogen atom (aN = 0.533 mT) and decrease of density at the aldehydic proton (aH = 0.334 mT). Chenges of half-wave potentials of the individual furfural derivatives correlate well with changes in the respective Hammett constants of the substituents.

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Comparison of Spin Density Calculation Methods for Various Alkyl-Substituted 9,10-Anthraquinone Anion Radicals in the Solution Phase

Magnetic Resonance in Chemistry ◽

10.1002/(sici)1097-458x(199611)34:11<898::aid-omr985>3.0.co;2-r ◽

1996 ◽

Vol 34 (11) ◽

pp. 898-902 ◽

Cited By ~ 4

Author(s):

Jussi Eloranta ◽

Virpi Vatanen ◽

Antti Grönroos ◽

Mikko Vuolle ◽

Reijo Mäkelä ◽

...

Keyword(s):

Spin Density ◽

Solution Phase ◽

Calculation Methods ◽

Density Calculation ◽

Spin Density Calculation ◽

Anion Radicals

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Electrochemical evaluation of electron acceptor materials

Canadian Journal of Chemistry ◽

10.1139/v84-322 ◽

1984 ◽

Vol 62 (10) ◽

pp. 1877-1885 ◽

Cited By ~ 39

Author(s):

R. O. Loutfy ◽

C. K. Hsiao ◽

B. S. Ong ◽

B. Keoshkerian

Keyword(s):

Electron Acceptor ◽

Methylene Chloride ◽

Energy Levels ◽

Mercury Electrode ◽

Transport Processes ◽

Reduction Potentials ◽

Half Wave ◽

Intermediate Anion ◽

Wave Reduction ◽

Anion Radicals

The electrochemical half-wave reduction potential (E1/2) of 33 electron acceptor molecules in dry methylene chloride has been measured by cyclic voltammetry (CV) at a mercury electrode. The differences in E1/2 values for the reversible reduction to the corresponding anion radicals reflect the electronic influence of the substituent at different ring positions.The measurements of the half-wave reduction potentials provided a convenient method for determining the conducting energy levels of the electron relay molecules in condensed media. Repetitive potential cycle measurements provided information on the chemical stability and cyclability of the intermediate anion radicals formed during electron transport processes.

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Current—potential responses for a tetrahemic protein: a method of determining the individual half-wave potentials of cytochrome c3 from desulfovibrio desulfuricans strain Norway

Electrochimica Acta ◽

10.1016/0013-4686(81)85068-2 ◽

1981 ◽

Vol 26 (8) ◽

pp. 1001-1004 ◽

Cited By ~ 63

Author(s):

P. Bianco ◽

J. Haladjian

Keyword(s):

Protein A ◽

Desulfovibrio Desulfuricans ◽

Cytochrome C3 ◽

Half Wave ◽

The Individual ◽

Current Potential

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Unpaired Electron Spin Density Distribution across Reduced [2Fe-2S] Cluster Ligands by 13Cβ-Cysteine Labeling

Inorganic Chemistry ◽

10.1021/acs.inorgchem.7b02676 ◽

2017 ◽

Vol 57 (2) ◽

pp. 741-746 ◽

Cited By ~ 3

Author(s):

Alexander T. Taguchi ◽

Yoshiharu Miyajima-Nakano ◽

Risako Fukazawa ◽

Myat T. Lin ◽

Amgalanbaatar Baldansuren ◽

...

Keyword(s):

Density Distribution ◽

Spin Density ◽

Electron Spin ◽

Unpaired Electron ◽

Spin Density Distribution ◽

Electron Spin Density ◽

Cysteine Labeling

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The nitro group in aromatic anion radicals-a donor-type substituent

Bulletin of the Academy of Sciences of the USSR Division of Chemical Science ◽

10.1007/bf00850076 ◽

1972 ◽

Vol 21 (11) ◽

pp. 2389-2391

Author(s):

Z. V. Todres ◽

A. A. Pozdeeva ◽

V. A. Chernova ◽

S. I. Zhdanov

Keyword(s):

Nitro Group ◽

Donor Type ◽

Anion Radicals

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Metallkomplexe von Heteroarenen, VII: Bis(2,3,5,6-tetramethyl-η6-pyrazin)vanadium, der erste Bis(aren)metall-Komplex mit vier N-Atomen in der Koordinationssphäre / Metal Complexes of Heteroarenes, VII: Bis(2,3,5,6-tetramethyl-η6-pyrazine)vanadium, the First Bis(arene)metal Complex with Four N Atoms in the Coordination Sphere

Zeitschrift für Naturforschung B ◽

10.1515/znb-1993-1117 ◽

1993 ◽

Vol 48 (11) ◽

pp. 1581-1588 ◽

Cited By ~ 8

Author(s):

Mathias Nowotny ◽

Christoph Elschenbroich ◽

Andreas Behrendt ◽

Werner Massa ◽

Sigrid Wocadlo

Keyword(s):

Spin Density ◽

Lone Pair ◽

Hyperfine Coupling Constant ◽

Metal Ring ◽

Torsional Angle ◽

Redox Potentials ◽

X Ray Crystallography ◽

Phase Combination ◽

Nitrogen Lone Pair ◽

The Individual

Cocondensation of 2,3,5,6-tetramethyl-pyrazine with vanadium atoms affords [2,3,5,6-(CH3)4-η6-1,4-C4N2]2V (6) which has been studied by X-ray crystallography, EPR-spectro-scopy and cyclic voltammetry. As shown by unequal metal ring-atom distances (V—C = 219.6, V—N = 210.9 pm) the ligand in 6 is folded along the N—N axis (dihedral angle 13.6°). The conformation adopted by the cyclic ligands in the crystal has a torsional angle of 44.2° which comes close to the angle of 45° expected for maximum back-bonding, the filled vanadium orbitals 3 dx2-γ2and 3 dxy interacting separately with unoccupied b3u(π*) orbitals of the individual pyrazine rings. The hyperfine coupling constant a(51V) = 4.45 mT attests to comparatively small spin density at the metal nucleus. It is proposed, that substantial transfer of spin density is effected by V 3dz2→ag(σn+) overlap, the latter function representing the in-phase combination of the nitrogen “lone pair” orbitals. Contrary to bis(η6-phosphinine)vanadium 8, for the pyrazine complex 6 only the anion 6⁻ is formed reversibly in cyclovoltammetry, oxidation to 6+ being irreversible. However, in common with 8, the redox potentials for 6 show pronounced anodic shifts. Attempts towards η6-coordination of 2,4,6-trimethyl-1,3,5-triazine failed. Apparently, the 1:1 ratio of CH3/N is insufficient to furnish the triazine ring with the appropriate combination of π-donor and δ-acceptor properties essential for synergetic bond formation.

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ESR studies of alkyl aryl ketyl radicals

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19813264 ◽

1981 ◽

Vol 46 (13) ◽

pp. 3264-3269 ◽

Cited By ~ 2

Author(s):

Eva Kutejová-Maťašová ◽

Andrej Staško ◽

Ľubomír Malík

Keyword(s):

Spin Density ◽

Unpaired Electron ◽

Aromatic Nucleus ◽

Alkyl Aryl ◽

Marked Influence ◽

Benzenecarboxylic Acids

Reactions of R1-substituted benzenecarboxylic acids (R1 = H, Me, Et, and t-Bu) with R2MgX (R2 = Et and n-Pr) in the presence of nickel produce ketyl radicals R1-Ar-CO.-R2. Average values of splitting constants of the protons in the aromatic nucleus are a2 = a6 = 0.48 mT, a4 = 0.53 mT, and a3, a5 < 0.12 mT. In some cases for R2 = n-Pr interaction of gamma protons is also observed with a2 = 0.04 mT. The investigated substituents R1, R2 have no marked influence on distribution of spin density of the unpaired electron.

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INDO calculations of spin densities. II. Further calculations on nickel(II) complexes and on a variety of acetylacetone complexes

Australian Journal of Chemistry ◽

10.1071/ch9710031 ◽

1971 ◽

Vol 24 (1) ◽

pp. 31 ◽

Cited By ~ 25

Author(s):

MJ Scarlett ◽

AT Casey ◽

RA Craig

Keyword(s):

Spin Density ◽

Aliphatic Amines ◽

Indo Method ◽

Aromatic Nitriles ◽

Indo Calculations ◽

Spin Densities

Calculations of spin density on the ligand have been made by the INDO method on nickel(II) complexes of quinoline N-oxides, water, ammonia, aliphatic amines, aromatic nitriles, and isonitriles as well as on the acetylacetonates of a variety of metals. Three cases are distinguished: (1) the ligand could be considered purely as a cation or anion; (2) the ligand could be considered as a hybrid of cation and anion; (3) neither of these approaches is satisfactory, indicating that neglect of metal orbitals causes serious errors.

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