Structural and electrochemical studies of novel bis(mu-methoxo)diiron complexes: observation of Fe(III)Fe(IV) and Fe(IV)Fe(IV) states resonating with phenoxyl radicals.
Novel diiron complexes with an Fe2(mu-OMe)2 core were studied as models of the active site of nonheme iron-containing enzymes. X-ray crystal structures of the complexes showed the existence of two types of ligand folding-parallel and twisted-both of which have four virtually equivalent phenolato groups sticking out from the Fe2O2 rhombic plane. Cyclic voltammetry measurements revealed two or more distinct redox waves in a region of relatively high potential, in addition to known Fe(II)/Fe(III) redox waves in a region of lower potential. These new peaks were assigned to the high-valence state of iron atoms, that is, Fe(III)Fe(IV) and Fe(IV)Fe(IV), resonating with the phenoxyl radical(s). The split width of the redox waves ranged from 0.14 to 0.20 eV, which may be a measure of the electronic interaction of the phenolate groups through the Fe2(mu-OMe)2 core.
Houjou
Hirohiko
H
Nanoarchitectonics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan. houjou@iis.u-tokyo.ac.jp
Kanesato
Masatoshi
M
Hiratani
Kazuhisa
K
Mandon
Dominique
D
D018360:Crystallography, X-Ray; D004563:Electrochemistry; D005609:Free Radicals / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*
D005609:Free Radicals; D008024:Ligands; D009942:Organometallic Compounds; D010636:Phenols; D007501:Iron