Structure and catalase-like activity of two new diMn(III) complexes with symmetric N2O3 Schiff Base ligands

SANDRA SIGNORELLA; CLAUDIA PALOPOLI; VERÓNICA DAIER; HERNÁN BIAVA; DIEGO MORENO; MÓNICA DE GAUDIO

Mérida (México)

Conferencia; 36th International Conference on Coordination Chemistry; 2004

Academia de Ciencias de México y la American Chemical Society

1,5-Bis(3-methylsalicylidenamino)pentane-3-ol) (L1) and 1,5-bis(2-hydroxybenzophenylidenamino)pentan-3-ol (L2) yield [Mn2(m-OAc)(m-OMe)(L)(MeOH)2]Br (1: L = L1; 2: L = L2) when reacted with Mn(OAc)3.4H2O in methanol in the presence of NaBr. Complexes 1 and 2 (fig. 1) are structural mimics of the MnIII2 form of Mn catalases. The length of the aliphatic bridging units of these ligands modulates the Mn…Mn separation to around 2.92 Å, a value slightly shorter than the Mn...Mn distance found in the MnIII2 form of these enzymes. The two complexes catalyse the dismutation of more than 1000 equiv. of H2O2, with saturation kinetics and KM values similar to the enzyme. Complex 1 is one of the more efficient complexes of the X-salpentOH family (salpentOH = 1,5-bis(salicylideneamino)pentan-3-ol) to disproportionate H2O2.