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Complexes of organotin compounds RSnCl with bisand trisphosphonate derivatives of 2,6-di- tert-butyl-4-methylphenol (ionol) were synthesized. X-ray diffraction studies were carried out for some of them. The redox properties of the synthesized compounds were characterized by cyclic voltammetry. Antioxidant/prooxidant activity of the complexes was studied using a new electrochemical method based on measuring the rate of hydrogen atom transfer to the stable radical 2,2´-diphenyl-1-picrylhydrazyl (DPPH). The data obtained were compared with the results of studying activity of the compounds during lipid peroxidation (LP) in biological samples. A correlation is observed between the results on antioxidant activity obtained by electrochemical DPPH test and using biological samples. Unlike the initial organotin compounds, the synthesized complexes have antioxidant activity, whereas phosphorus-containing phenols exhibit the properties of efficient antioxidants and chelating agents. [ABSTRACT FROM AUTHOR]

Electrochemical method for the evaluation of antioxidative activity of compounds based on their reaction with the stable radical, 2,2-diphenyl-1-picrylhydrazyl, was suggested with monitoring of the reaction by cyclic voltammetry (CVA). Antioxidative properties of new ferrocene derivatives Fc(L)R (where Fc is the ferrocenyl, R is the fragment of 2,6-di- tert-butylphenol or its aromatic analog, L is the spacer) were studied. Anodic oxidation of the compounds Fc(L)R, which contain azomethine and 2,6-di- tert-butylphenol moities, proceeds in three steps, that suggests a possibility of intramolecular proton-coupled electron transfer process. Conjugates of ferrocene and 2,6-di- tert-butylphenol are efficient antioxidants. [ABSTRACT FROM AUTHOR]

The complex investigation of paramagnetic (17-electron) iron and ruthenium closo-metallacarboranes with chelate diphosphine ligands 3,3-(PhP(CH)PPh)-3-Cl- closo-3,1,2-MCBH (M = Fe, n = 2, 3; Ru, n = 4), o-phenylenecycloboronated 3-Cl-3,3,8-[InlineMediaObject not available: see fulltext.] ( n = 3, 4; R = H or Me), and bis( o-cycloboronated) [InlineMediaObject not available: see fulltext.] ( n = 4, 5) was performed using cyclic voltammetry and matrix-activated laser desorption/ionization time-of-flight (MALDI-TOF) spectrometry. Some diamagnetic iron and ruthenium exo-nido- and commo-complexes were studied using the same methods. A relationship between the redox potentials of the metallacarborane complexes and their stability and transformations under the MALDI-TOF conditions was established. [ABSTRACT FROM AUTHOR]