6415-12-9Relevant articles and documents
Reactivity of boroxine. Reactions with azomethane and azoethane
Kaldor, Andrew,Pines, Ira,Porter, Richard F.
, p. 1418 - 1423 (1969)
A product of the reaction of boroxine with azomethane and azoethane has been identified as a 1:1 azoalkane-borine addition compound. Structural information based on infrared and nuclear magnetic resonance data indicate that the product has the unsymmetrical configuration (Chemical Equation Presented).
Indirect determination of self-exchange electron transfer rate constants
Nelsen, Stephen F.,Ismagilov, Rustem F.,Gentile, Kevin E.,Nagy, Mark A.,Tran, Hieu Q.,Qu, Qinling,Halfen, DeWayne T.,Odegard, Amy L.,Pladziewicz, Jack R.
, p. 8230 - 8240 (2007/10/03)
Second-order rate constants k(ij)(obsd) measured at 25 °C in acetonitrile by stopped-flow spectrophotometry for forty-four electron transfer (ET) reactions among fourteen 0/+1 couples [three aromatic compounds (tetrathiafulvalene, tetramethyltetraselenafulvalene, and 9,10-dimethyl- 9,10-dihydrophenazine), four 2,3-disubstituted 2,3-diazabicyclo[2.2.2]octane derivatives, six acyclic hydrazines, and the bridgehead diamine 1,5- diazabicyclo[3.3.3]undecane] and seventeen compounds and forty-seven reactions from a previous study (J. Am. Chem. Soc. 1997, 119, 5900) [three p- phenylenediamine derivatives, four ferrocene derivatives, and ten tetraalkylhydrazines] are discussed. When all 91 k(ij)(obsd) values are simultaneously fitted to Marcus's adiabatic cross rate formula k(ij)(calcd) = (k(ii)k(jj)K(ij)f(ij))(1/2), ln f(ij) = (ln K(ij))(2/4) ln((kii)k(jj)/Z2), best-fit self-exchange rate constants, k(ii)(fit), are obtained that allow remarkably accurate calculation of k(ij)(obsd); k(ij)(obsd)/k(ij)(calcd) is in the range 0.5-2.0 for all 91 reactions. The average difference without regard to sign, |ΔΔG(+)(ij)|, between observed cross reaction activation free energy and that calculated using the k(ii)(fit) values and equilibrium constants is 0.13 kcal/mol. The ΔG(+)(ii)(fit) values obtained range from 2.3 kcal/mol for tetramethyltetraselenafulvalene(0/+) to 21.8 kcal/mol for tetra-n-propylhydrazine(0/+), corresponding to a factor of 2 x 1014 in k(ii)(fit). The principal factor affecting k(ii)(fit) for our data appears to be the internal vertical reorganization energy (λ(v)), but k(ii)(fit) values also incorportate the effects of changes in the electronic matrix coupling element (V). Significantly smaller V values for ferrocenes and for hydrazines with alkyl groups larger than methyl than for aromatics and tetramethylhydrazine are implied by the observed ΔG(+)(ii)(fit) values.
Absolute Rates of Recombination and Disproportination of Dimethylaminyl Radicals
Lazarou, Yannis G.,Papagiannakopoulos, Panos
, p. 9133 - 9140 (2007/10/02)
The absolute rate constants for the recombination (kr) and disproportionation (kd) reactions of dimethylaminyl radicals were determined at room temperature with the very low pressure reactor (VLPR) technique.The obtained values were kr = (1.70 +/- 0.19) x 1E-12 cm3 molecule-1 s-1 and kd = (4.19 +/- 0.52) x 1E-12 cm3 molecule-1 s-1, and the ratio kd/kr was 2.32 +/- 0.26.The transition-state geometries for both recombination and disproportination reactions are loose, with the N...N bond length ca. 3.5 Angstroem and the N...H...C distance ca. 4.4 Angstroem.In the recombination TS, the four C-N...N bending modes are ca. 90 cm-1 and play a significant role in the formation of the N-N bond in tetramethylhydrazine.In the disproportionation TS, the two (in-plane and out-of-plane) vibrational modes of the metathetic hydrogen are ca. 110 cm-1 and are essential in the formation of the N-H bond in dimethylamine.
