Reactivity of tert-butylperoxyl radical with manganese(III), cobalt(II), and nickel(II) salicylidene Schiff base chelates
✍ Scribed by Levon A. Tavadyan; Hakob Gh. Tonikyan; Makich V. Musaelyan; Aram E. Barsegyan; Seyran H. Minasyan; John R. J. Sorenson
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 240 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
Abstract
Salicylidene Schiff base chelates (R,R)‐(–)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediaminomanganese(III) chloride, (R,R)‐(–)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediaminocobalt(II), N,N′‐bis(salicylidene)‐ethylenediaminocobalt(II), N,N′‐bis(salicylidene)ethylenediaminonickel(II), and N,N′‐bis(salicylidene)ethylenediaminoaquacobalt(II), as well as (R,R)‐(–)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)1,2‐cyclohexanediamine, were kinetically examined as antioxidants in the scavenging of tert‐butylperoxyl radical (tert‐butylOO^•^). Absolute rate constants and corresponding Arrhenius parameters were determined for reactions of tert‐butylOO^•^ with these chelates in the temperature range −52.5 to −11°C. High reactivity of tert‐butylOO^•^ with Mn(III) and Co(II) salicylidene Schiff base chelates was established using a kinetic electron paramagnetic resonance method. These salicylidene Schiff base chelates react in a 1:1 stoichiometric fashion with tert‐butylOO^•^ without free radical formation. Ultraviolet–visible spectrophotometry and differential pulse voltammetry established that the rapid removal rate of tert‐butylOO^•^ by these chelates is the result of Mn(III) oxidation to Mn(IV) and Co(II) oxidation to Co(III) by tert‐butylOO^•^. It is concluded that removal of alkylperoxyl radical by Mn(III) and Co(II) salicylidene Schiff base chelates may partially account for their biological activities. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 431–439, 2007