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

Herein, we describe the synthesis and X-ray structure of a new heteropentanuclear complex (2) containing a [(Fe2Zn3II)-Zn-III(mu-OH)(3)] structural unit and the unsymmetrical ligand H2L2-et. The molecular structure of (2) shows that it is formed by a basic dinuclear [Fe-III(mu-OH)Zn-II(L-2-et)] unit that is connected to a second dinuclear [Fe-III(mu-OH)Zn-II(L-2-et)] unit through a hydroxo bridge while a third ZIP 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 (FeZnII)-Zn-III omplex containing the same ligand, the association with 2,4-BDNPP is significantly decreased.