ESR spectrum of

The ESR spectrum of the pyridazine radical anion, generated by the action of sodium or potassium, has been reported, and oxidation of 6-hydroxypyridazin-3(2//)-one with cerium(IV) sulfate in sulfuric acid results in an intense ESR spectrum (79TL2821). The self-diffusion coefficient and activation energy, the half-wave potential (-2.16 eV) magnetic susceptibility and room temperature fluorescence in-solution (Amax = 23 800cm life time 2.6 X 10 s) are reported. 

Tile low-temperature ESR spectrum of the anion radical of purine disclosed that about 45% of the spin density is localized at position 6 (80BCJ1252), although a single very broad signal for N(7) and N(9) did not allow discussion of the tautomerism. 

Figure 2.1 Ligand hyperfine structure in the ESR spectrum of Na2[(Ir, Pt)Cl6].6H20. (Reproduced with permission from Proc. R. Soc., London, Ser. A, 1953, 219, 526.)...

Figure 2.33 The ESR spectrum of [Rh(tmpp)2]2+ in CH2Cl2/toluene at 8 K. (Reprinted with permission from J. Am. Chem. Soc., 1991, 111, 5504. Copyright (1991) American Chemical Society.)...

The ESR spectrum of the furan radical anion indicates that the Cem-0 bond is ruptured in the electron transfer process whereby the oxygen atom acquires the negative charge and the C-2 end of the open ring possesses a free radical character ... 

Irradiation of the molecular radical anion of DESO, which has a yellow color, with light of X = 350-400 nm partially restores the red color and the ESR spectrum of the radical-anion pair. Similarly to the case of DMSO-d6 a comparison of the energetics of the photodissociation of the radical anion and dissociative capture of an electron by a DESO molecule permits an estimation of the energy of the hot electrons which form the radical-anion pair of DESO. This energy is equal to 2eV, similarly to DMSO-d6. The spin density on the ethyl radical in the radical-anion pair of DESO can be estimated from the decrease in hfs in comparison with the free radical to be 0.81, smaller than DMSO-d6. 

The ESR spectrum of the thioxanthene S, S-dioxide radical anion itself shows that the two possible conformers coexist, since the two methylene protons are not equivalent. In the case of the 9-monoalkyl derivatives, the large coupling constant observed for the 9-proton leads to the conclusion that the 9-substituent is in the boat equatorial position as in II1 F Thus the radical anions and the neutral molecule display different conformations. The protons in the 9-position of the radical anions of cis-9-methylthioxanthene S-oxides (2, n — 1, R1 = H, R2 = CH3) have an appreciable coupling constant10 which suggests that these radical anions have the substituent in the pseudo-axial position. Furthermore, in the radical anions the S—O bond is pseudo-axial. These situations are exactly the opposite of that observed for the neutral compound. 

The ESR spectrum of C6H6 " trapped in CFCI3 at 15 K is shown in Figure la and agrees with that reported previously [18]. The principal values of the hyperfine coupling were obtained from previous ESR and ENDOR measurements [17, 18]. The best agreement with experiment was obtained with the axes oriented as in Table 4. In the latter study, the simulated ENDOR spectra were insensitive to the orientation of the tensor axes, however, and the assignment was made on the basis of molecular orbital calculations [9]. The tensor data are reproduced here for convenience (see Table 4). 

Figure 1. ESR spectrum of dibenzo-p-dioxin in TFMS acid...

Trisacetylacetonecobalt(III) oxidises phenols to phenoxyl radicals at 71-120 °C in chlorobenzene with simple second-order kinetics, E = 33 kcal.mole" and AS = 13.6 eu) . When 2,4,6-tcrt-butylphenol was employed, the characteristic ESR spectrum of the phenoxyl radical was obtained with an intensity corresponding to almost quantitative conversion, viz. 

Fig.S. Correlation between the integrated area of the seven line ESR spectrum (of Cu-H-Y, Cu-MCM-22 and Cu-VPl-5) and conversion of L-tyrosine, phenol, o-cresol and m-cresol (Curves A-D, respectively).

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