Dioxygen binding to complexes with Fe(II)2(mu-OH)2 cores: steric control of activation barriers and O2-adduct formation.
A series of complexes with [Fe(II)(2)(mu-OH)(2)] cores has been synthesized with N3 and N4 ligands and structurally characterized to serve as models for nonheme diiron(II) sites in enzymes that bind and activate O(2). These complexes react with O(2) in solution via bimolecular rate-limiting steps that differ in rate by 10(3)-fold, depending on ligand denticity and steric hindrance near the diiron center. Low-temperature trapping of a (mu-oxo)(mu-1,2-peroxo)diiron(III) intermediate after O(2) binding requires sufficient steric hindrance around the diiron center and the loss of a proton (presumably that of a hydroxo bridge or a yet unobserved hydroperoxo intermediate). The relative stability of these and other (mu-1,2-peroxo)diiron(III) intermediates suggests that these species may not be on the direct pathway for dioxygen activation.
Kryatov
Sergey V
SV
Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, Massachusetts 02155, USA.
Taktak
Sonia
S
Korendovych
Ivan V
IV
Rybak-Akimova
Elena V
EV
Kaizer
József
J
Torelli
Stéphane
S
Shan
Xiaopeng
X
Mandal
Sanjay
S
MacMurdo
Vicki L
VL
Mairata i Payeras
Antoni
A
Que
Lawrence
L
D018360:Crystallography, X-Ray; D004563:Electrochemistry; D005296:Ferrous Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry*
D005296:Ferrous Compounds; D008024:Ligands; D010100:Oxygen