Hydrolytic and oxidative catalytic activities of bio-inspired dinuclear metal complexes

Abstract: A number of homo- and heterodinuclear complexes have been synthesized as structural and functional models for the the active sites of phosphoesterases and soluble methane monooxygenases. The complexes are based on four new dinucleating ligands containing a central, potentially bridging, phenolate moiety. The hydrolytic activity of the complexes was examined by exploring the ability of the complexes to catalyze the hydrolysis of (2,4-dinitrophenyl)-phosphate (BDNPP), which functions as a model for DNA. Three dizinc complexes and one heterodinuclear Fe(III)Mn(II) complex were studied. Computational modelling was undertaken to explore the potential reaction mechanisms and the transition states of the phosphoester hydrolysis reactions. Speciation studies based on potentiometric titration coupled with mass spectrometric measurements were used to understand the identities of the active catalysts at certain pH. Dinuclear oxo-bridged Fe(III) complexes of two new ligands have been studied as catalysts for alkane and alkene oxidations, using hydrogen peroxide/acetic acid as the ultimate oxidant. Low temperature UV-Vis and mass spectrometry techniques suggest that peroxide-bridged diiron intermediates are formed in the oxidation reactions.