Synthesis and reactivity of a 4His enzyme model complex

Abstract

A new iron(II) complex has been prepared and characterized. [Fe(TrIm)₄(OTf)₂] (1, TrIm = 1-tritylimidazole). The solid state structure of 1 has been determined by X-ray crystallography. Compound 1 crystallizes in triclinic space group P, with a = 13.342(7) Å, b = 13.5131(7) Å and c = 13.7025(7) Å. The iron center resides in distorted octahedral geometry coordinated to four equatorial imidazole groups and two axial triflate oxygens groups. The complex is high spin between 20 K and 300 K as indicated by variable field variable temperature magnetic measurements. A fit of the magnetic data yielded g = 2.24 and D = −0.80 cm⁻¹. A large HOMO–LUMO gap energy (3.89 eV) exists for 1 indicating high stability. Addition of H₂O₂ or ^tBuOOH to 1 results in formation of an oxygenated intermediate which upon decomposition results in oxidation of the trityl substituent on the imidazole ligand.