Development of Highly Functionalized Dimetal Complexes

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The purpose of this research project is development of highly functionalized di-and polynuclear metal complexes by controlling the nature of the coordination environment around metal ions.Control of Magnetic interaction of heterbdinuclear meatl complexes : A series of heterodinuclear bis(μ-hydroxo)Cr(III)Ni(II) complexes, [(phen)_2Cr(μ-OH)_2Ni(Me_n-tpa)](ClO_4)_3, with sterically bulky tpa (tris(2 pyridylmethyl)amine) derivatives having 6-methyl group(s) (n = 0 - 3) was prepared. Introduction of the 6 methyl group(s) onto the pyridyl group(s) results in systematic elongation of the Ni-N bond distances, leading to the systematic magnetic interaction change from weak antiferromagnetic interaction to relatively strong ferromagnetic interaction. This can be interpreted in terms of lie lowering of the d-orbital energies on the nickel centers, which leads to a decrease of the antiferromagnetic contribution. The present results shows that the magnetic interaction-can be controlled by the d-orbital energies of the. Metal ions by modifying the coordination environments.Control of dioxygen reactivity of cbppef(I) complexes : A copper(I) complex ([Cu(L)]^+) having a tripodal tetradentate ligand (bis(6-methyl-2-pyridylmethyl)(2-pyridylethyl)amine) reacted with dioxygen at -80℃ to genertate a bis(μ-oxo)dicopper(III) complex whose structure was determined by X-ray crystallography. The bis(μ-oxo)dicopper(III) complex showed a reversible conversion with a precursor copper (I) complex by bubbling N_2 gas at -80 - 55℃ and also showed a monooxygenase activity for the supporting ligand at higher temperature. Such reversible 4 electron reduction and oxidation of between O_2 and O^<2-> is of particular importance for dioxygen activation and water oxidation chemistry.