Electronic absorption spectra for free hydrazyl radicals, their ionic forms and initial hydrazines

Abstract

AbstractsThe results of the calculations of n-n* transition energies of some free hydrazyl radicals, their ionic forms and initial hydrazines by the SCF-MO-LCAO method with restricted configuration interaction are presented. The comparison of the data obtained with the electronic spectra experimentally found, revealed that the absorption of radical solutions in the visible area was due to the electronic structure of radical molecules, the contribution of ionic forms to the absorption being negligible.On prtsente les rtsultats de calculs des tnergies de transition n-n* de quelques radicaux libres d'hydrazyle, de leurs formes ioniques et des hydrazines initiales par la mtthode SCF-MO-LCAOavec CI restreinte. En comparant ces rtsultats-ci avec les spectres exptrimentaux on trouve que I'absorption dans la rtgion visible est due B la structure Clectronique des radicaux, la contribution des formes ioniques B l'absorption &ant negligeable.Die Resultate von SCF -Mo-LcAo-cr-Berechnungen der n-a*-Ubergangsenergien einiger freien Hydrazylradikalen, ihrer Ionenformen und Initialhydrazinen werden angegeben. Der Vergleich dieser Resultate mit den Experimentalspektra zeigt, dass die Absorption im Sichtbaren von der Elektronenstruktur der Radikalen herruhrt, wobei der Beitrag der Ionenformen zur Absorption unbedeutend ist.

The Chemistry of DPPH· Free Radical and Congeners

“…λ max (nm), pK a , E ox (V) and bond dissociation energy (BDE) values (kcal/mol) for selected compounds [17,27,39,46,56,61]. All these redox or acid-base processes can be followed by color change [62]. Table 2 also compiles the wavelength values where hydrazyl free radicals, their parent hydrazines or the corresponding anions have the maximum absorption.…”

“…All these redox or acid-base processes can be followed by color change [ 62 ]. Table 2 also compiles the wavelength values where hydrazyl free radicals, their parent hydrazines or the corresponding anions have the maximum absorption.…”

Synthesis and spectral comparison of electronic and molecular properties of some hydrazines and hydrazyl free radicals

“…6 These properties make them useful in acid-base and redox processes that are accompanied by color changes. 7 The best-known hydrazyl free radical is 2,2-diphenyl-1-picrylhydrazyl (DPPH). It is a stable solid, soluble in organic solvents, with a violet color similar to that of potassium permanganate.…”