Iron(III) complexes with a tripodal N3O ligand containing an internal base as a model for catechol intradiol-cleaving dioxygenases
2007 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, no 22, 9364-9371 p.Article in journal (Refereed) Published
A bis(mu-alkoxo)-bridged dinuclear iron(III) complex [Fe(L)(NO3)](2)(NO3)(2) [1; HL = NN-bis(2-pyridylmethyl)-N-(2hydroxyethyl)amine] of the tripodal N3O ligand was prepared as a biomimetic model for the intradiol-cleaving dioxygenase enzymes. The reaction of 1 and catechol in the presence of excess triethylamine gave the catecholate (CAT) chelate b is(u -al koxo) -bridged dinuclear iron(Ill) complex [Fe(L)(CAT)12 (2). The molecular structures of complexes 1 and 2 were determined by X-ray crystallography. Diiron complexes 1 and 2 contain the same bis(u-alkoxo)diiron diamond core. All heteroatoms (N3O) of the ligand are coordinated to the iron center in complex 1 with two pyridine nitrogen atoms on the axial bonds, while one of the pyridyl arms of the ligand is left uncoordinated in complex 2. The interaction of the diiron complex 1 and 3,5-di-tert-butylcatechol (H2DBC) was investigated by electronic and mass spectroscopy. Complex 1 displays the intradiol-cleaving dioxygenase activity, and the coordinate ethoxyl arm of the ligand is capable of accepting the proton from catechol, which mimics the function of Tyr447 in the. protocatechuate 3,4-dioxygenase as an internal base. The spectrop h oto metric titration experiment indicates the relatively low demand of the external base (0.8 equiv based on Fe3+) for attaining the highest dioxygenase activity of complex 1. The reaction rate of the reactive intermediate [Fe(HL)(DBC)](+) with dioxygen is 0.38 M-1 s(-1) determined by kinetic studies.
Place, publisher, year, edition, pages
2007. Vol. 46, no 22, 9364-9371 p.
reactive functional-model, nonheme iron enzymes, protocatechuate 3,4-dioxygenase, crystal-structure, active-sites, (catecholato)iron(iii) complexes, tetradentate ligands, angstrom resolution, oxidative cleavage, 1,2-dioxygenase
IdentifiersURN: urn:nbn:se:kth:diva-17057DOI: 10.1021/ic700664uISI: 000250345400046ScopusID: 2-s2.0-35848936091OAI: oai:DiVA.org:kth-17057DiVA: diva2:335100
QC 201005252010-08-052010-08-05Bibliographically approved