2018年9月4日以色列理工学院Graham de Ruiter教授学术报告
Metal-Metal and Metal-Ligand Cooperation for Activating Small Molecules: Unprecedented Rate Acceleration for Oxygen Atom Transfer
报告主题：Metal-Metal and Metal-Ligand Cooperation for Activating Small Molecules: Unprecedented Rate Acceleration for Oxygen Atom Transfer
报告人：Graham de Ruiter教授 以色列理工学院（Technion - Israel Institute of Technology）
The versatility by which iron-containing metalloenzymes are able to activate and oxygenate C–H bonds with molecular oxygen has sparked much interest in the underlying mechanism. It has been shown that high-valent iron metal centers bearing terminal metal-oxo motifs are commonly invoked in the oxygenation step, and their formation has been studied in many monometallic iron model complexes. Despite the intense research efforts, terminal metal-oxo motifs on multi-metallic scaffolds are rare. Recently, we presented a new class of tetra-iron complexes that are site differentiated. In these complexes, three six-coordinate iron centers form a trimetallic “core” that is connected to a fourth unique coordinatively unsaturated apical iron center. We have also shown that treating – for example – [LFe3(PhPz) 3OFe] [OTf] 2(PhPz = Ph pyrazolate) with oxygen-atom transfer reagents results in regioselective intramolecular hydroxylation of an arene C–H bond. These reactivity patterns suggest the involvement of a rare FeIV-oxo motif on well-defined multi-metallic scaffold. Here we show that the selectivity and reactivity of the different metal clusters can be modulated by regulating the oxidation state of the trimetallic “core” resulting in intramolecular electron transfer pathways that are able to alter the reactivity of terminal iron-oxo species (e.g. MIV-O vs. MIII-O), and unprecedented rate acceleration in oxygen atom transfer reactions.