A new heteropentanuclear complex containing the [Fe2IIIZn3II(μ-OH)3] structural motif as a model for purple acid phosphatases

Abstract Herein, we describe the synthesis and X-ray structure of a new heteropentanuclear complex (2) containing a [Fe2IIIZn3II(μ-OH)3] structural unit and the unsymmetrical ligand H2L2-et. The molecular structure of (2) shows that it is formed by a basic dinuclear [FeIII(μ-OH)ZnII(L2-et)] unit that is connected to a second dinuclear [FeIII(μ-OH)ZnII(L2-et)] unit through a hydroxo bridge while a third ZnII ion is coordinated by the pendant 1,2-ethanediamine groups of H2L2-et, resulting in the pentanuclear complex. Kinetic studies on the hydrolysis of the substrate 2,4-BDNPP (bis(2,4-dinitrophenyl)phosphate) reveal that (2) shows diesterase activity. While the kinetic activity is comparable to the corresponding dinuclear FeIIIZnII complex containing the same ligand, the association with 2,4-BDNPP is significantly decreased.