Synthesis and Characterization of Carboxylate-Rich Complexes Having the {Fe₂(μ-OH)₂(μ-O₂CR)}³⁺ and {Fe₂(μ-O)(μ-O₂CR)}³⁺ Cores of O₂-Dependent Diiron Enzymes

Abstract

The {Fe2(mu-OH)2(mu-O2CR)}3+ and {Fe2(mu-O)(mu-O2CR)}3+ cores of the carboxylate-bridged diiron(III) centers in the enzyme active sites were reproduced by small molecule model complexes that were prepared through direct oxygenation of the mononuclear iron(II) complexes. Upon oxygenation of [Fe(O2CArTol)2(Hdmpz)2], where -O2CArTol is 2,6-di(p-tolyl)benzoate and Hdmpz is 3,5-dimethylpyrazole, [Fe2(mu-OH)2(mu-O2CArTol)(O2CArTol)3(OH2)(Hdmpz)2] was generated and characterized to share close physical properties with sMMOHox, including delta = 0.45 (2) mm/s, DeltaEQ = 1.21 (2) mm/s, and J = -7.2 (2) cm-1. The compound [Fe2(mu-O)(mu-O2CAr4-FPh)(O2CAr4-FPh)3(Hdmpz)3], where -O2CAr4-FPh is 2,6-di(4-fluorophenyl)benzoate, with delta = 0.51 (2) mm/s, DeltaEQ = 1.26 (2) mm/s, and J = -117.4 (1) cm-1, was isolated as the oxygenation product of [Fe(O2CAr4-FPh)2(Hdmpz)2].

A Five-Coordinate Copper(II) Complex Constructed from Sterically Hindered 4-Chlorobenzoate and Benzimidazole: Synthesis, Crystal Structure, Hirshfeld Surface Analysis, DFT, Docking Studies and Antibacterial Activity

“…The combined effect of the sterically hindered carboxylate ligand and the intramolecular hydrogen-bonding interactions changes the binding mode of the carboxylate ligands from bidentate to monodentate. This rather unusual environment around the central atom was previously observed in Cu, Fe and Co complexes [54][55][56].…”

μ-Oxo-bridged diiron(iii) complexes of tripodal 4N ligands as catalysts for alkane hydroxylation reaction using m-CPBA as an oxidant: substrate vs. self hydroxylation

“…2,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] A few m-oxo-bridged diiron(II) complexes were developed as structural mimics of the active center of sMMO and related enzymes, in which the active site coordination environment of the sMMO have been mimicked. 2,[36][37][38][39][40][41] Also, the involvement of high valent Fe IV ]O species in the alkane hydroxylation reaction was proved and are characterized the species by X-ray crystallographic techniques. 2,[42][43][44][45][46] The diiron(III) complexes of tris(2pyridylmethyl)amine (TPA) and related ligands are known as effective sMMO models.…”

Iron Complexes of Dendrimer-Appended Carboxylates for Activating Dioxygen and Oxidizing Hydrocarbons

“…In the presence of dioxygen, several of these complexes convert to di(μ-hydroxo)diiron(III) species that mimic the oxidized state of MMOH. 6,[8][9][10][11][12] In some of this chemistry, the formation of peroxodiiron(III) and/or di(μ-oxo)diiron (IV) intermediates was suggested, although no direct evidence for such species was obtained. 6…”