Development of Functional Metal Complexes Having Active Oxygen Species Controlled by Coordination Sphere

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The purpose of this project is the development of metal complexes having active-oxygen species. In order to syntheses such complexes, we have developed new coordination environments, where the first and second coordination spheres can cooperatively function.1. Synthesis of (μ-η^2:η^2-Peroxo)Cu(II)_2 Complexes as Functional Models for Tyrosinase and Methane Monooxygenase: We have succeeded in synthesis of (μ-η^2:η^2-peroxo)Cu(II)_2 complexes, [Cu_2(O_2) (H-L)]^<2+> (oxy-H-1), where H-L = 1, 3-bis [bis (6-methyl-2-pyridylmethyl)aminomethyl]benzene, which can perform not only hydroxylation of the m-xylyl linker of H-L, but also epoxidation of styrene via an electrophilic addition of the peroxide to the C=C bond. In addition, oxy-H-1 can oxidize various aliphatic C-H bonds having the bond dissociation energies (BDE) 75 - 92 kcal mol^<-1> via H-atom abstraction. A linear correlation between log k (the second order rate constants of oxidation) and BDE was observed.2. Synthesis of (μ-Peroxo)diiron (III) Complex as a Functional Model for Toluene Monooxygenase: We have succeeded in synthesis of two types of peroxodiiron (III) complexes, [Fe_2(LPh4) (RCO_2) (O_2)]^<2+> (R = Ph_3C (oxy-l) and Ph (oxy-2)), the former leads to regioselective hydroxylation of a phenyl group of LPh4 and the latter exhibits reversible deoxygenation (LPh4 = N,N,N',N'-tetrakis[(1-methyl-2-phenyl-4-imidazolyl)methyl]-1,3-diamino-2-propanolate). This is the first example of the peroxodiiron (III) complex which is capable of arene hydroxylation. The reactions mimic toluene monooxygenase and hemerythrin reactivity, respectively.