ic7b01418_si_001.pdf (9.41 MB)
Tuning the Diiron Core Geometry in Carboxylate-Bridged Macrocyclic Model Complexes Affects Their Redox Properties and Supports Oxidation Chemistry
journal contribution
posted on 2017-09-05, 18:20 authored by Fang Wang, Sabine Becker, Mikael A. Minier, Andrei Loas, Megan N. Jackson, Stephen J. LippardWe introduce a novel platform to
mimic the coordination environment of carboxylate-bridged diiron proteins
by tethering a small, dangling internal carboxylate, (CH2)nCOOH, to phenol-imine macrocyclic ligands
(H3PIMICn). In the presence of an external bulky carboxylic
acid (RCO2H), the ligands react with [Fe2(Mes)4] (Mes = 2,4,6-trimethylphenyl) to afford dinuclear [Fe2(PIMICn)(RCO2)(MeCN)] (n = 4–6)
complexes. X-ray diffraction studies revealed structural similarities
between these complexes and the reduced diiron active sites of proteins
such as Class I ribonucleotide reductase (RNR) R2 and soluble methane
monooxygenase hydroxylase. The number of CH2 units of the
internal carboxylate arm controls the diiron core geometry, affecting
in turn the anodic peak potential of the complexes. As functional
synthetic models, these complexes facilitate the oxidation of C–H
bonds in the presence of peroxides and oxo transfer from O2 to an internal phosphine moiety.