14149-96-3Relevant academic research and scientific papers
Free electron transfer mirrors rotational conformers of substituted aromatics: Reaction of benzyltrimethylsilanes with n-butyl chloride parent radical cations
Brede, Ortwin,Hermann, Ralf,Naumov, Sergej,Zarkadis, Antonios K.,Perdikomatis, Gerasimos P.,Siskos, Michael G.
, p. 2267 - 2275 (2004)
The rotation motion of a larger substituent of an aromatic ring is accompanied by the electron density fluctuation of the highest occupied molecular orbitals. For benzyltrimethylsilanes p-R3-C 6H4-○-CR1-R2
Quenching of singlet oxygen by oxygen- and sulfur-centered radicals: Evidence for energy transfer to peroxyl radicals in solution
Darmanyan, Alexandre P.,Gregory, Daniel D.,Guo, Yushen,Jenks, William S.,Burel, Laure,Eloy, Dominique,Jardon, Pierre
, p. 396 - 403 (2007/10/03)
Quenching of singlet oxygen luminescence at 1.27 μm by PhS., PhSO., and peroxyl radicals PhOO., t-BuOO., PhCH2OO., Ph2CHOO. and Ph3COO. was studied in liquid solution. The quantum yields of decomposition of different initiators which lead to the formation of free radicals were measured by using nanosecond transient absorption. This allowed determination of singlet oxygen O2(1Δ(g)) quenching rate constants by the radicals. They are 8 M-1 s-1 for the sulfur-centered radicals and (2-7) x 109 M-1 s-1 for peroxyl radicals in acetonitrile. The rapid quenching is attributed to energy transfer quenching by the peroxyls, which have an n → π* transition leading to a low-lying 2A' state above their 2A'' ground state. PhSO. is shown computationally not to have such a low-lying 2A' state. There may be a very low-lying 2B1 state, for PhS., but it is apparently not an efficient acceptor of electronic energy from O2(1Δ(g)).
New Mechanistic Probes of Hydride Abstraction from Rhenium-Alkyl Complexes (η5-C5H5)Re(NO)(PPh3)(R) by Ph3C+PF6-; Evidence for Initial Electron Transfer
Bodner, Gerardo S.,Gladysz, J. A.,Nielsen, Merete Folmer,Parker, Vernon D.
, p. 1757 - 1764 (2007/10/02)
The mechanism of hydride abstraction from rhenium-alkyl complexes R-(Re) ((Re) = (η5-C5H5)Re(NO)(PPh3)) by Ph3C+PF- is probed by study of the equilibrium R-(Re) + Ph3C+ ->/.+ + Ph3C. (eq v) and the effect of oxygen on the rate and deuterium kinetic isotope effect.Equilibrium constants K5 are determined in CH2Cl2 at 208 K from reversible potential measurement for R = PhCH2 (1, 2.5 x 10-5), (CH3)2CHCh2 (2, 7.9 x 10-3), and Ph(CH3)CH (3, 5.0 x 10-2).When generated electrochemically in separate experiments, R-(Re).+ and Ph3C. are stable under the reaction conditions.Upon mixing CH2Cl2 solutions of the reactants in (v), rapid reactions ensue giving Ph3CH and hydride abstraction products derived from R-(Re).Thus, if an electron transfer mechanism is operative, very rapid hydrogen atom exchange must take place between R-(Re).+ and Ph3C. to displace the unfavorable equilibria (v) to the right.Nearly diffusion controlled rate constants are found for the reaction between Ph3C. and O2, suggesting that Ph3C. formed in (v) could be trapped by O2 and diverted from the pathway leading to Ph3CH.Rate enhancements of ca. an order of magnitude are observed when reactions are carried out in the presence of oxygen, while the rhenium products are essentially unchanged.A deuterium kinetic isotope effect, kH/kD = 5.4, is found for reactions of PhCH2-(Re) and PhCD2-(Re) under nitrogen but not in the presence of oxygen.This indicates that in the presence of O2 rate control switches from hydrogen atom transfer to electron transfer.In the presence of O2, as much as 70 percent of the organic product is benzophenone, arising from decomposition of Ph3COOH.It is concluded that hydride transfer from R-(Re) to Ph3C+PF6- most likely takes place by an initial electron transfer followed by hydrogen atom transfer to either Ph3C. or Ph3COO., depending upon whether O2 is present.
The Strength of the R-O2. Bond in Peroxy-radicals and the Reversibility of the Reaction R. + O2 ->/.
Finkel'shtein, E. I.,Gerasimov, G. N.
, p. 570 - 572 (2007/10/02)
An equation is proposed for the calculation of the R-O2. bond strength in peroxy-radicals: DR-O2. = DR-H - 254.4 kJ mol-1.The calculated equilibrium constants of the reactions R. + O2 ->/-
