Novel iron(III) complexes with imidazole containing tripodal ligands as model systems for catechol dioxygenases

Functional models for catechol dioxygenases: Iron(III) complexes of cis-facially coordinating linear 3N ligands

“…In contrast, the extradiol dioxygenases utilise iron(II) cofactor ligated by two histidine and one glutamic acid in a square-pyramidal geometry. Several bioinorganic modeling studies [13][14][15][16][17][18][19][20][21][22][23][24] have focused on the structural and spectroscopic characterization of iron(III) complexes of tetradentate linear and tripodal and tetraaza macrocyclic ligands as structural and functional models for the catecholateiron(III) form of catechol dioxygenase. In a vast majority of these studies the oxygenation products reported are consistent with intradiol-cleavage.…”

Structures and Properties of Novel Mononuclear Iron(III) Complexes with Benzimidazole Containing Tripodal Tetradentate Ligands

“…The cleavage of dbc exhibits pseudo first order kinetics due to an excess of dioxygen [2]. As proposed by Que et al, the dioxygenase activity of iron(III) complexes depends on the Lewis acidity of the metal center [1 b, 8, 15].…”

“…Some complexes of the ligands listed in Table 3 have also been tested for their catechol 1,2-dioxygenase activity [2]. In these compounds small moieties like pyridine and methylimidazole cause higher reaction rate constants.…”

“…A yellow product precipitates from this solution upon standing. Recrystallization from methanol yields the white product Catechol cleaving activity: The catechol 1,2-dioxygenase activities of in situ prepared complexes were tested according to a procedure described elsewhere [2]. The measurements of each complex were carried out at least three times.…”

“…In solution replacement of the chloro ligands occurs forming the reactive species for catechol binding. Selected complexes of different ligands with similar coordination modes are listed in Table 3 for comparison [2,3].…”