Keywords: Zn II Fe III complex / Fe II Fe III complex / Purple acid phosphatases / Phosphate ester hydrolysisThe heterodinuclear Zn II Fe III complex 1 and the isostructural Fe II Fe III complex 2 with the dinucleating ligand from 2,6-bis[{bis(2-pyridylmethyl)amino}methyl]-4-methoxyphenol (HBPMOP, 3) were prepared and characterized by X-ray crystallography. Solution studies (UV/Vis spectroscopy; electrochemistry) are described. A pH-induced change in the coordination spheres of the metal centers is seen. These complexes serve as models for the mixed-valence oxidation state in purple acid phosphatases. The cleavage acceleration of the activated phosphodiester 2-hydroxypropyl p-nitrophenyl

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A new heterodinuclear Zn II Fe III µ-phenoxy complex has been prepared and isolated from the unsymmetrical ligand 2-{[bis(2-hydroxybenzyl)]amino}methyl-6-{[2-pyridinylmethyl)amino]methyl}-4-methylphenol (H 3 L 1 ), which provides two distinct N-and O-rich donor sets. The regioselective complexation is confirmed in solution by 1 H NMR studies (comparison of the spectra obtained from H 3 L 1 and HL 2 − a ligand with only the N-donor set available − and a zinc salt).

Five new dinuclear model complexes for zinc-containing phosphatases with dinucleating ligands have been prepared and characterized by single-crystal X-ray crystallography. The heterodinuclear, µ-alkoxo-bridged zinc(II)−iron(III) complexes 1−3 contain the symmetric ligands N,N,NЈ,NЈ-tetrakis[2-(5,6-dimethyl)benzimidazolylmethyl]-1,3-diamino-2propanol (Htdmbpo) and N,N,NЈ,]benzimidazolylmethyl}-1,3-diamino-2-propanol (Hthebpo), and the asymmetric ligand N,N-bis[2-(4,5dimethyl)benzimidazolylmethyl]-NЈ,NЈ-bis(2-pyridylmethyl)-1,3-diamino-2-propanol (Hbdmbbppo), respectively. X-ray crystallography revealed that the zinc center exhibits a trigonal-bipyramidal coordination, while the octahedral coordination sphere of the iron center is completed by a solvent molecule. In contrast, the zinc complexes 4 and 5, which also [a]

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