SYNTHESIS, STRUCTURAL CHARACTERIZATION, AND EXTRADIOL OXYGENATION OF IRON-CATECHOLATO COMPLEXES WITH HYDROTRIS(PYRAZOLYL)BORATE LIGANDS

Fe(III)-catecholato complexes with the hydrotris(pyrazolyl)borate liga nds (Tp(R); R denotes substituents of the 3- and 5-positions of the py razolyl 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 Tp(R) ligands. O-2 treatment o f Tp(Pri2)Fe(III)(DBC) (DBCH2 = 3,5-di-tert-butylcatechol) affords as major products those derived from extradiol cleavage of the catechol, although a highly hindered Tp(R) ligand complex, Tp(But,Pri)Fe(III)(DB C), is relatively inert toward O-2.