- Laser Flash Photolysis of HClO, ClO(-), HBrO, and BrO(-) in Aqueous Solution. Reactions of Cl- and Br-Atoms
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Spectra and rate constants of reactions were measured of chlorine and bromine atoms formed by photolysis of aqueous solutions of hypochlorous and hypobromous acids and their salts with light of wavelength 248.5 and 308 nm.Chlorine and bromine atoms in aqueous solution behave like weak oxygen acids showing the pKa-values 5.1 and 10.5, respectively.Exchanges of water molecules bound to the halogen atoms are fast processes. - Keywords: Chemical Kinetics / Laser Flash Photolysis / Photochemistry / Radicals / Solutions
- Klaening, Ulrik K.,Wolff, Thomas
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p. 243 - 245
(2007/10/02)
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- Anion radical oxidation of nickel(II) macrocyclic complexes. Pulse radiolysis of (2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene) nickel(II) in sodium bromide solution
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The oxidation of NiII(CR+4H) [CR+4H = 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene, α isomer] by Br2- and subsequent chemistry of Ni(III) intermediates have been studied by pulse radiolysis. The initial electron transfer is diffusion controlled and results in an initial product which exhibits characteristics of a Ni(III)-Br- adduct. The stability of this adduct, especially in acidic media, is dependent on bulk bromide concentration, demonstrating an equilibrium process of the form NiIII(CR+4H)(Br-)(H2O) + H2O ? NiIII(CR+4H)(H2O)2 + Br-, with Keq = 360 M-1. The pK of dissociation for the aquated species is 4.0 ± 0.8. At pH >5 displacement of the bound bromide is first order in [OH-] with a rate constant of 6 × 109 M-1 s-1. Disappearance of the NiIII(CR+4H)(OH-) intermediate is also pH dependent, suggesting amine dissociation in the ligand and formation of an unstable ligand radical leading to a final product with increased ligand unsaturation.
- Morliere,Patterson
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p. 1458 - 1465
(2008/10/08)
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