Synthesis, Characterization And Catalytic Properties Of Iron, Copper Complexes Inspired By Nature

In the nature, enzymes including the copper and iron widely exist in the organism, and they can effectively catalyze various biochemical reactions in very mild conditions, promote the metabolism of the organism. Studing their structure and mechanism is advantageous to simulate the reaction of synthesis of efficient biological inorganic catalysts. We mainly study the [FeFe]-hydrogenase and hydrocarbon activation enzyme in the following two aspects.Firstly, we synthesized and characterized some benzene-bridged diiron hexacarbonyl complexes: [Fe2(μ-S)2(CO)6-o-C6H2(OOC-o-C5H4N)2](2), [Fe2(μ-S)2(CO)6-o-C6H2(OH)(OOC-o-C5H4N)](3), [Fe2(μ-S)2(CO)6-o-C6H2(OOC-o-C6H2(OOC-o-C6H4OCH3)2](4), [Fe2(μ-S)2(CO)6-o-C6H2(OH)(OOC-o-C6H4OH)](5) and [Fe2(μ-S)2(CO)6-o-C6H2(OOC-o-C6H4OH)2](6). Electrochemical studies of these complexes show that [FeFe]-hydrogenase including pyridine exist proton coupled electron transfer(PCET) in the presence of acid and the process with the pKa of acid has a linear relationship. The greater is pKa value of acid, the smaller potential moves to the positive direction. For the reduction process, their catalytic activity is affected from acid strength and themselves. We also found that [FeFe]-hydrogenase model complexes containing alkaline groups are proton electrochemical reduction of catalytic activity in strong acid.The second part is the combination catalyzed C-H bond activationin enzyme in nature and industrial production of phenol, we study the direct synthesis of phenol by one-step method. Four copper(II) complexes with multidentate ligands, 1([CuL1Cl2]), 2([Cu(HL2)Cl2]), 3([Cu2(L2)2](ClO4)2) and 4([CuL3(HOCH3)Cl O4]) are synthesized and characterized. We found that among the copper(II) complexes exist the correlation between reduction potential and catalytic performance. The greater is reduction potential value, the higher is conversion rate of benzene. The radical is most likely a hydroxyl radical when H2O2 is employed as an oxidant. That addition of radical scavengers such as TEMPO could severely suppress the catalysis confirmed that the catalysis undergoes a radical mechanism. These studies providesome clues how to suppress the over-oxidation of the product phenol to improve the selectivity/yield in the homogeneous catalytic hydroxylation of benzene.