The esr spectrum of the diphenylmethyl radical

Bassindale, Alan R.; Bowles, A. J.; Hudson, Andrew; Jackson, Richard A.; Schreiner, Kurt; Berndt, A.

doi:10.1016/s0040-4039(00)79806-6

Cited by 23 publications

(11 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The relative intensities of these four lines are approximately 4 : 2 : 2 : 2, respectively. In a previous ESR study of the related diphenylmethyl radical, [13] the meta protons were reported to have the smallest coupling (3.78 MHz) followed by the ortho and para protons (10.36 and 11.76 MHz, respectively). Since the meta protons should also produce the smallest couplings in 1, the observed intensity pattern in the special TRIPLE spectrum is therefore consistent with an assignment based on four equivalent meta protons (3.00 MHz), two sets of two equivalent ortho protons (7.85 and 8.80 MHz) and two equivalent para protons (10.00 MHz).…”

Section: Resultsmentioning

confidence: 86%

“…• ) fragment in 1 (m-H = 3.00 MHz, o-H = 8.30 MHz, p-H = 9.95 MHz) compared with the diphenylmethyl radical (m-H = 3.78 MHz, o-H = 10.36 MHz, p-H = 11.76 MHz) [13] is expected and consistent with that observed for the triphenylsilane radical, SiPh 3 Si(OCPh 2 • ) (m-H = 3.45 MHz, o-H = 8.85 MHz, p-H = 9.75 MHz). [14] The observed in-equivalencies in spin distribution to the two phenyl rings at 250 K and the reduction in the hfc of the paraproton at lower temperatures (190 K) is most likely caused by the hindered rotation about the O-CPh 2…”

Section: Resultsmentioning

confidence: 95%

See 1 more Smart Citation

A CW‐EPR, ENDOR and special TRIPLE resonance study of a novel magnesium ketyl radical

Murphy

McDyre

Carter

et al. 2011

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

In this paper, the paramagnetic properties of a novel magnesium ketyl radical (compound 1), formed by reduction of benzophenone with a dimeric Mg(I) complex in the presence of dimethylaminopyridine, are described. Using CW EPR, ENDOR and special TRIPLE resonance, the spin distribution in the radical has been explored at variable temperatures (200-298 K). At 298 K, most of the unpaired spin is found to be confined to the (OCPh(2)(•)) fragment based on the hyperfine couplings (hfc's) of o-H = 8.30, m-H = 3.00 and p-H = 9.95 MHz. Smaller hfc's to (25)Mg (5.54 MHz) and (14)N(DMAP) (0.90 MHz) were also evidenced in the 298 K EPR spectrum, indicating some spin delocalisation onto the Mg(Nacnac)(DMAP) fragment. At lower temperatures, restricted rotations of the diphenyl rings create an inequivalent spin distribution in the two rings, with o(1)-H = 8.80, o(2)-H = 7.85, m-H = 3.00 and p-H = 10.00 MHz.

show abstract

Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 95%

A CW‐EPR, ENDOR and special TRIPLE resonance study of a novel magnesium ketyl radical

Murphy

McDyre

Carter

et al. 2011

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

show abstract

“…between these experimental values and an empiriwhile it is commonly accepted that the transition cal calculation of the rotational barrier using radical state for isomerization of symmetrically stability arguments. The resonance stabilization substituted (1,2-across the double bond) olefins is energy of the radicals was e s t h a t e d from esr spin 1.2-biradical-like in nature (3, 41, this study density data (7). The rotational barrier of tetraphvides experimental evidence of the validity of this enylethylene, for example, was calculated by simidea.…”

Section: Introductionmentioning

confidence: 92%

Merostabilization in radical ions, triplets, and biradicals. 6. The excited state behaviour of para-substituted tetraphenylethylenes

Leigh¹,

Arnold²

1981

Can. J. Chem.

View full text Add to dashboard Cite

This paper i~ t1edicatc.d to Prof. G. Ham~notzd on the occ~asion of his 60th birthday WILLIAM J . LEIGH and DONALD R. ARUOLD. Can. J . Chem. 59. 3061 (1981). The half-wave oxidation and reduction potentials. measured by cyclic voltammetry. of tetraphenylethylene and a series of para-substituted (cyano, methyl. and methoxy) derivatives are found to correlate with o+ and 0 -values respectively. The deviations from these correlations that are observed for one of the derivatives (unsymmetrically substituted) are attributed to merostabilization.The nature of the first excited singlet state of these compounds is investigated by spectroscopic and photochemical means. Quantum yields for the direct c i~ -trans photoisomerization demonstrate that this provides the dominant pathway for decay of the singlet state. The n ,n * triplet energies are estimated from a qualitative investigation of the relative efficiencies of triplet-sensitized cis-trans isomerization as a function of sensitizer triplet energy. On a Ctudie la nature du premier etat singulet excite de ces composes par la photochimie et la spectroscopie. Les rendements quantiques de la photoisomerisation directe cis-trans demontrent le mecanisme principal de la desintegration de l'etat singulet. On a evalue les energies du triplet n.x* a partir d'une recherche qualitative sur I'efficacite relative de I'isomerisation c i s -t r a~~s sen~ibilisee par un triplet en fonction de I'energie du triplet sensibilisateur.[Traduit par le journal]

show abstract

“…To gain more insight into the reaction mechanism, reaction progress was investigated by ESR spectroscopy. The ESR spectrum of the diphenylmethane radical [11] (2 in Scheme 1) was observed, as shown in Figure 1. The two-band hyperfine structure in the spectrum centered at the calibrated g iso % 2.004 indicates that in the radical there is a strong magnetic-coupled nucleus possessing the I = 1/2 nuclear spin leading to the 2I + 1 = 2 hyperfine peaks.…”

mentioning

confidence: 99%

“…Moreover, the current of the oxidation was also optimized. Below 20 mA of the current the reaction proceeded slowly in a low yield, while no improvement was observed beyond the 20 mA (entries [10][11][12]. Therefore, we chose 20 mA as the current of electrolysis in the reaction.…”

mentioning

confidence: 99%

Direct Electrosynthesis of Ketones from Benzylic Methylenes by Electrooxidative CH Activation

Zha

et al. 2013

Chemistry A European J

View full text Add to dashboard Cite

Electrify your chemistry! Direct electrosynthesis of ketones from benzylic methylenes in an undivided cell was realized in moderate to good yields. In this electrosynthesis, electrons instead of conventional oxidants and catalysts are employed to make the reaction environmentally benign. Moreover, the reaction intermediate radical was detected by ESR spectroscopy and the reaction mechanism was clarified.

show abstract

The esr spectrum of the diphenylmethyl radical

Cited by 23 publications

References 4 publications

A CW‐EPR, ENDOR and special TRIPLE resonance study of a novel magnesium ketyl radical

A CW‐EPR, ENDOR and special TRIPLE resonance study of a novel magnesium ketyl radical

Merostabilization in radical ions, triplets, and biradicals. 6. The excited state behaviour of para-substituted tetraphenylethylenes

Direct Electrosynthesis of Ketones from Benzylic Methylenes by Electrooxidative CH Activation

Contact Info

Product

Resources

About