Comparing the reactivity of an oxoiron(iv) cation radical and its oxoiron(v) tautomer towards C–H bonds

Abstract

An oxoiron(iv) cation radical is generated upon two-electron oxidation of an iron(iii) complex bearing an electron-rich methoxy substituted bTAML framework and characterized via multiple spectroscopic techniques and density functional theory (DFT).

Functional Model of Compound II of Cytochrome P450: Spectroscopic Characterization and Reactivity Studies of a FeIV–OH Complex

“…The presence of pre-edge features corresponds to 1s to 3d quadrupole transitions and dipole excitations of the core electrons into the valence 3d states hybridized with ligand p orbitals. − A pre-edge area of 19.3 units was obtained for 1 at 7113.97 eV, which is close and consistent with that of previously studied five-coordinated ferric centers, demonstrating pre-edge areas of ∼14.1 units at 7113 eV (Figure A inset, 3B, Table S3). By contrast, complex 3 demonstrates a pre-edge area of 23.5 units at 7114.32 eV (Figure A inset, 3B, Table S3) comparable to the reported high-spin Fe­(IV) oxo complexes, where an area of ∼25 units has been observed. ,, The lesser intense pre-edge feature of complex 3 vs iron­(IV) oxo complexes of tetraamido macrocyclic ligands (TAMLs) ,, is due to its higher coordination environment and more centrosymmetric geometry in comparison to five-coordinated Fe IV complexes. Indeed, centrosymmetric complexes have been shown to have a decreased intensity in their pre-edge features due to an increase in the metal 4p mixing into the 3d orbitals, contributing toward the electric dipole 1s to 4p character of this transition .…”

“… 33 By contrast, complex 3 demonstrates a pre-edge area of 23.5 units at 7114.32 eV ( Figure 3 A inset, 3B, Table S3 ) comparable to the reported high-spin Fe(IV) oxo complexes, where an area of ∼25 units has been observed. 38 , 40 , 44 The lesser intense pre-edge feature of complex 3 vs iron(IV) oxo complexes of tetraamido macrocyclic ligands (TAMLs) 36 , 45 , 46 is due to its higher coordination environment and more centrosymmetric geometry in comparison to five-coordinated Fe IV complexes. Indeed, centrosymmetric complexes have been shown to have a decreased intensity in their pre-edge features due to an increase in the metal 4p mixing into the 3d orbitals, contributing toward the electric dipole 1s to 4p character of this transition.…”