New diamino-diheterophenol ligands coordinate iron(III) to make structural and functional models of protocatechuate 3,4-dioxygenase.

Three diamino, dihetero-phenol ligands were synthesized by sequential Mannich condensations. These ligands were combined with FeCl3 to produce three five-coordinate Fe(III) complexes that are structural models for the enzyme 3,4-PCD. The three Fe(III) complexes were characterized by elemental analysis, single crystal X-ray diffraction studies, UV-vis spectroscopy, and cyclic voltammetry. Combining the Fe(III) complexes with 3,5-di-t-butylcatechol and O2 resulted in oxidative cleavage similar to the function of 3,4-PCD.