Autoxidation of Ni(II) and Co(II) tetra, penta and hexaglycine complexes accelerated by oxy sulfur radicals

Journal of the Brazilian Chemical Society

Luciana B. Carvalho¹  María V. Alipázaga¹  Denise Lowinsohn¹  Mauro Bertotti¹  Nina Coichev¹ 

[1] ,Universidade de São Paulo Instituto de Química São Paulo SP ,Brazil

关键词: nickel;    cobalt;    pentaglycine;    hexaglycine;    sulfite;   

DOI  :  10.1590/S0103-50532006000700030

来源: SciELO

【 摘 要 】

The autoxidation of Ni(II) and Co(II) complexes with tetra, penta and hexaglycine, in borate medium, is accelerated by sulfur(IV) species (H2SO3, HSO3- and SO3(2-)). The formation of Ni(III) and Co(III) complexes was followed spectrophotometrically at 325 and 265 nm, respectively. Electrochemical techniques were also employed to characterize the generation of these complexes. The autoxidation rate increases with S(IV) concentration and is maximum at pH @ 8.5. The process is autocatalytic with Ni(III) or Co(III) acting as initiators, formed by spontaneous oxidation by oxygen. The dependence of the pseudo first order rate constant with sulfite concentration showed evidences of back or parallel reactions with formation of mixed ligand complex prior to the oxidation step.

【 授权许可】

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