Two Cobalt(III) Schiff Base Complexes of the Type [Co(ABC)(DE)X]: Facile Synthesis, Characterization, Catechol Oxidase and Phenoxazinone Synthase Mimicking Activity

Abstract

AbstractTwo new mononuclear cobalt(III) Schiff base complexes with azide or thiocyanate [Co(L1)(L′)(N3)] (1) and [Co(L2)(L“)(NCS)] (2) {where HL1=2((2(piperidin‐1‐yl)ethylimino)methyl)‐6‐ethoxyphenol, HL2=2‐((3(dimethylamino)propylimino)methyl)‐6‐methoxyphenol, HL′=1‐acetyl‐2‐naphthol and HL”=2,4‐pentanedione} have been synthesized and characterized by single crystal X‐ray diffraction studies. Both complexes may be represented by a general formula: [Co(ABC)(DE)X], where ABC, DE and X represent tridentate, bidentate and monodentate ligands respectively. Both complexes are reactive towards the aerial oxidation of 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) and o‐aminophenol (OAPH), and kinetics of the reactions are monitored spectrophotometrically. Analyses of the kinetic data reveal that complex 2 is better catalyst than complex 1 for both oxidation reactions. Tentative mechanistic implications of the catalytic oxidation reactions are also discussed. Mechanistic investigations of the catalytic behaviors indicate that the oxidation reactions proceed through catalyst‐substrate intermediates.