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3869204 
Journal Article 
Insight into the origin of catechol oxidase activity in a rare Mn-II/mn(III) mixed valence ion pair complex: An account of comparative biomimetic catalytic study 
Panja, A; Jana, NCh; Adak, S; Pramanik, K 
2017 
1 
Inorganica Chimica Acta
ISSN: 0020-1693
EISSN: 1873-3255 
459 
113-123 
WOS:000397369600014 
A mixed valence ion pair complex, [Mn-II(ntb)Cl][Mn-III(Br(4)Cat)(2)(H2O)(2)]center dot 4H(2)O (2) and a manganese(III) compound, (Et3NH)(2)[Mn(Br(4)Cat)(2)(H2O)(2)][Mn(Br(4)Cat)(2)(H2O)(Pm)]center dot H2O (3), where ntb is tris(2-benzimidazolylmethyl)amine, Br(4)CatH(2) is tetrabromocatechol and pm is pyrimidine, have been synthesized and the solid state structures were determined by X-ray crystallography. Compound 2 was prepared by the reaction of [Mn(ntb)Cl]Cl center dot 2.5MeOH (1) and tetrabromocatechol in aerobic condition, and is a rare example of complex ion pair in the class of metal-dioxolene chemistry. Compound 2 exhibits strong cate-cholase activity in which both Mn(II) and Mn(III) centers are catalytically active as suggested by the reactivity study of compounds 1 (identical to the cationic part of 2) and 3 (comprising an anionic part similar as in 2). The mechanistic investigation discloses that Mn(III) center in complex 3 and in anionic part of complex 2 oxidises 3,5-DTBCH2 and itself reduces to Mn(II) center with concomitant production of 3,5-DTBQ and H2O2. Whereas both dioxygen and substrate bound Mn(II) center in cationic part of 2 and in compound 1 is the active species in the catalytic cycle in which complete reduction of molecular oxygen to H2O occurs. Although some mixed valence manganese(II/III) complexes are known to exhibit catechol oxidase, the present report only provides the role of individual metal ions in a mixed valence manganese(II/III) system to the mechanistic pathways of functioning catechol oxidase activity. (C) 2017 Elsevier B.V. All rights reserved. 
Redox active catecholate ligand; Rare manganese(II/III) mixed valence complex; Crystal structure; Catechol oxidase activity; Mechanistic pathway and mass spectrometry