IQUIR   05412
INSTITUTO DE QUIMICA ROSARIO
Unidad Ejecutora - UE
artículos
Título:
Synthesis, Structure and Catalase-like Activity of Dimanganese(III) Complexes of 1,5-Bis[(2-hydroxy-5-X-benzyl)(2-pyridylmethyl)amino]pentan-3-ol (X = H, Br, OCH3)
Autor/es:
BIAVA, H.; PALOPOLI, C.; DUHAYON, C.; TUCHAGUES, J. P.; SIGNORELLA, S.
Revista:
INORGANIC CHEMISTRY
Editorial:
ACS
Referencias:
Año: 2008
ISSN:
0020-1669
Resumen:
ABSTRACTNew diMnIII complexes of general formula [Mn2L(μ-OR)(μ-OAc)]BPh4 (H3L = 1,5-bis[(2-hydroxy-5-X-benzyl)(2-pyridylmethyl)amino]pentan-3-ol, 1: X = H, R = Me, 2: X = OMe, R= Me, 3: X = Br, R = Me, 4: X = Br, R = Et) have been prepared and structurallycharacterized. The synthesized complexes possess a triply bridged (μ-alkoxo)2(μ-acetato)Mn23+ core, a short intermetallic distance of 2.95/6 Å modulated by the aliphaticspacers between the central alcoholato and N-amino donor sites, and the remainingcoordination sites of the two MnIII centres occupied by the six donor atoms of the polydentateligand. In DMF, complexes 1-3 are able to disproportionate more than 1500 eq. of H2O2without significant decomposition, with first-order dependence on catalyst and saturationkinetic on [H2O2]. Spectroscopic monitoring of the reaction mixtures revealed that the catalystconverts into [Mn2III(μ-O)(μ-OAc)L], which is the major active form during cycling. Overall,kinetics and spectroscopic studies of H2O2 dismutation by these complexes converge at acatalytic cycle between MnIII2 and MnII2 oxidation levels. Comparison to other alkoxo-bridgedcomplexes suggests that the binding mode of peroxide to the metal centre of the MnIII2 form ofthe catalyst is a key factor for tuning the Mn oxidation states involved in the H2O2 dismutation mechanism.