Study of the radical-cations of triethylamine and benzene derivatives by the optical detection of the EPR spectra of radical-ion Pairs

1982 ◽  
Vol 23 (3) ◽  
pp. 327-333 ◽  
Author(s):  
V. M. Grigoryants ◽  
O. A. Anisimov ◽  
Yu. N. Molin
Keyword(s):  
Optical Detection ◽  
Ion Pairs ◽  
Radical Cations ◽  
Epr Spectra ◽  
Benzene Derivatives

EPR spectra and structure of the radical cations of fluorinated benzenes

1997 ◽  
pp. 1625-1632 ◽  
Author(s):  
Akinori Hasegawa ◽  
Yoshiteru Itagaki ◽  
Masaru Shiotani
Keyword(s):  
Radical Cations ◽  
Epr Spectra

Metall-π-Komplexe yon Benzolderivaten, XIII Bis(methylthio-η-beiizol)chrom(0) Darstellung und Einsatz als zweizähniger Chelatligand/ Metal-π Complexes of Benzene Derivatives, XIII Bis(methylthio-η-benzene)chromium(0) Preparation and Function as a Bidentate Chelating Ligand

1981 ◽  
Vol 36 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Helmut Burdorf ◽  
Christoph Eischenbroich
Keyword(s):  
Nmr Spectra ◽  
Room Temperature ◽  
Radical Cations ◽  
Esr Spectra ◽  
Benzene Derivatives ◽  
Consecutive Reaction ◽  
H Nmr ◽  
Chelating Ligand ◽  
And Function ◽  
C Nmr

Abstract The thioanisole-π-complexes (methylthio-η-benzene)-(η-benzene)-chromium (2) and bis(methylthio-η-benzene)chromium (3) have been prepared via lithiation of bis(η-benzene)-chromium and consecutive reaction with dimethyldisulfide. 1H NMR and 13C NMR spectra of 2 and 3 as well as ESR-spectra of the corresponding radical cations 2.+ and 3.+ were recorded and analyzed. In contrast to C(η-arene)-Si and C(η-arene)-P bonds, C(y-arene)-S bonds are stable to solvolysis. With (norbornadiene)tetracarbonylmolybdenum, 3 readily forms [bis(methylthio-η-benzene)chromium]tetracarbonylmolybdenum (6) wherein 3 functions as a chelating ligand. 1H and 13C NMR evidence suggests, that at room temperature 6 undergoes rapid conformational interconversions.

EPR spectra of Fe3(CO)−11 ions and [Fe3(CO)−11]2 triplet ion-pairs trapped in single crystals of PPN+HFe3(CO)−11

1990 ◽  
Vol 223 ◽  
pp. 115-122 ◽  
Author(s):  
J.R. Morton ◽  
K.F. Preston ◽  
J.-P. Charland ◽  
P.J. Krusic
Keyword(s):  
Single Crystals ◽  
Ion Pairs ◽  
Epr Spectra

Elektronentransfer und Ionenpaar-Bildung, 27 [1, 2] Darstellung von Semichinon-Ionenpaaren durch Reduktion von Chinonen mit Tetraalkylammonium-boranat in aprotischen Lösungen: 1,10-Phenanthrolin-5,6-dion / Electron Transfer and Ion Pairing, 27 [1, 2] Preparation of Semiquinone Ion Pairs by Reduction of Quinones Using Tetraalkylammonium Boranate in Aprotic Salt Solutions: 1,10-Phenanthrolin-5,6-dione

1992 ◽  
Vol 47 (2) ◽  
pp. 288-300 ◽  
Author(s):  
H. Bock ◽  
P. Hänel
Keyword(s):  
Radical Anion ◽  
Nuclear Charge ◽  
Ion Pairs ◽  
Radical Cations ◽  
Ion Pair ◽  
Metal Salts ◽  
Multiply Charged ◽  
Counter Cation ◽  
Cation Charge ◽  
Spin Densities

Ion pairs of 1,10-phenanthrolin-5,6-dione radical anion [M · ⊖Me⊕n] ·⊕(n−1) with Me⊕n = Mg⊕⊕, Ca⊕⊕, Sr⊕⊕, Zn⊕⊕, Cd⊕⊕, Pb⊕⊕ and La⊕⊕⊕ are advantageously prepared in aprotic DMF solution containing appropriate metal salts Me⊕nX⊖ by using the ‘mild’ single-electron reducing agent tetra(n-butyl)ammonium-boranate R4N⊕BH4⊖ . For comparison, the ‘naked’ radical anion with the largely interaction-free [K⊕(2.2.2)-cryptand]⊕ counter cation is chosen, which is formed on reduction with potassium in THF solution of (2.2.2)-cryptand. Addition of excess Na⊕[B(C6H5)4]⊖ to the reduction solution only yields a solvent-separated ion pair (M · ⊖)DMF ··· (Na⊕)DMF, whereas in the presence of multiply charged counter cations Me⊕n the respective contact ion pair radical cations [M · ⊖Me⊕n] · ⊕(n−1) are formed. Their g values decrease with increasing nuclear charge of Me⊕n and their metal-s-spin densities increase with the effective counter cation charge n⊕/rMe⊕n. The ESR /ENDOR data recorded suggest Me⊕n complexation by the δ⊖OC -COδ⊖ chelate tongs and the ion pair stability, which is modified by the dielectric properties of the solvent used, may be rationalized by the Coulombic attraction between the radical anion M · ⊖ and the counter cations Me⊕n.

scholarly journals Electron and hydrogen self-exchange of free radicals of sterically hindered tertiary aliphatic amines investigated by photo-CIDNP

2013 ◽  
Vol 9 ◽  
pp. 437-446 ◽  
Author(s):  
Martin Goez ◽  
Isabell Frisch ◽  
Ingo Sartorius
Keyword(s):  
Ion Pairs ◽  
Activation Parameters ◽  
Radical Cations ◽  
Outer Sphere ◽  
Exchange Reactions ◽  
Radical Pairs ◽  
Time Resolved ◽  
Alkyl Radicals ◽  
Acid Base Equilibrium ◽  
Reorganization Energies

The photoreactions of diazabicyclo[2,2,2]octane (DABCO) and triisopropylamine (TIPA) with the sensitizers anthraquinone (AQ) and xanthone (XA) or benzophenone (BP) were investigated by time-resolved photo-CIDNP (photochemically induced dynamic nuclear polarization) experiments. By varying the radical-pair concentration, it was ensured that these measurements respond only to self-exchange reactions of the free amine-derived radicals (radical cations DH • + or α-amino alkyl radicals D • ) with the parent amine DH; the acid–base equilibrium between DH • + and D • also plays no role. Although the sensitizer does not at all participate in the observed processes, it has a pronounced influence on the CIDNP kinetics because the reaction occurs through successive radical pairs. With AQ, the polarizations stem from the initially formed radical-ion pairs, and escaping DH • + then undergoes electron self-exchange with DH. In the reaction sensitized with XA (or BP), the polarizations arise in a secondary pair of neutral radicals that is rapidly produced by in-cage proton transfer, and the CIDNP kinetics are due to hydrogen self-exchange between escaping D • and DH. For TIPA, the activation parameters of both self-exchange reactions were determined. Outer-sphere reorganization energies obtained with the Marcus theory gave very good agreement between experimental and calculated values of ∆G ‡ 298.

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