Synthesis, Structural Characterization, and Extradiol Oxygenation of Iron-Catecholato Complexes with Hydrotris(pyrazolyl)borate Ligands(,).

Abstract

Fe(III)−catecholato complexes with the hydrotris(pyrazolyl)borate ligands (TpR; R denotes substituents of the 3- and 5-positions of the pyrazolyl rings) are synthesized as structural and functional models for catechol dioxygenase enzymes. Coordination geometry of the Fe centers depends on the steric hindrance of the TpR ligands. O2 treatment of TpPri2FeIII(DBC) (DBCH2 = 3,5-di-tert-butylcatechol) affords as major products those derived from extradiol cleavage of the catechol, although a highly hindered TpR ligand complex, TpBut,PriFeIII(DBC), is relatively inert toward O2.