π-Frontier molecular orbitals in S = 2 ferryl species and elucidation of their contributions to reactivity.
S = 2 Fe(IV) ═ O species are key intermediates in the catalysis of most nonheme iron enzymes. This article presents detailed spectroscopic and high-level computational studies on a structurally-defined S = 2 Fe(IV) ═ O species that define its frontier molecular orbitals, which allow its high reactivity. Importantly, there are both π- and σ-channels for reaction, and both are highly reactive because they develop dominant oxyl character at the transition state. These π- and σ-channels have different orientation dependences defining how the same substrate can undergo different reactions (H-atom abstraction vs. electrophilic aromatic attack) with Fe(IV) ═ O sites in different enzymes, and how different substrates can undergo different reactions (hydroxylation vs. halogenation) with an Fe(IV) ═ O species in the same enzyme.
Department of Chemistry, Stanford University, Stanford, CA 94305, USA.
Martin
M
Srnec
Shaun D
SD
Wong
Jason
J
England
Lawrence
L
Que
Edward I
EI
Solomon
D002384:Catalysis; D002942:Circular Dichroism; D007501:Iron / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry*
C066317:ferryl iron; D007501:Iron; D010100:Oxygen