Fine Tuning of Structure and Reactivity of Dicopper-Dioxygen Complexes

用N-烷基-双[2-（2-吡啶基）乙基]胺三齿配体和N， N-二烷基-2-（2-吡啶基）乙胺双齿配体研究了铜(I)配合物与分子氧的低温反应。三齿配体主要提供（μ-η^2: η^2-过氧）二铜（II）配合物（侧对型过氧配合物），而双齿配体促进过氧物质的O-O键均解生成双（μ-氧）二铜（III）配合物。利用三齿配体负载的（μ-η^2: η^2-过氧）二铜（II）配合物，实现了酚类化合物与相应儿茶酚的高效氧合，为酪氨酸酶提供了良好的模型反应。另一方面，双（μ-氧）二铜（III）配合物经历脂肪族配体羟基化以及氧原子转移到硫化物，得到相应的亚砜。在双（μ-氧）二铜（III）配合物与10-甲基- 9,10 -二氢吖啶（AcrH_2）和1,4 -环己二烯（CHD）的反应中，一种新的活性氧中间体（μ-氧）（μ-氧）（μ-氧自由基）二铜（III）或四核铜氧配合物可能作为外部底物C-H键活化的真正活性氧。用最小n -烷基取代基（甲基）的配体评价了双（μ_3-氧）三核铜（II， II， III）的混合价配合物。系统地讨论了上述反应的机理细节以及配体对铜(I)-二氧反应性的影响。除了铜-二氧配合物外，一种类似类型的镍-二氧配合物以及铜-二硫配合物已经被开发出来，以便进一步了解金属蛋白的氧化还原功能

Reaction of copper(I) complexes with molecular oxygen have been examined using a series of N-alkyl-bis[2-(2-pyridyl)ethyl]amine tridentate ligands and N, N-dialkyl-2-(2-pyridyl)ethylamine didentate ligands at low temperature. The tridentate ligands predominantly provide (μ-η^2 : η^2-peroxo)dicopper(II) complexes (side-on type peroxo complex), while the didentate ligands enhance O-O bond homolysis of the peroxo species to produce bis(μ-oxo)dicopper(III) complexes. With the (μ-η^2 : η^2-peroxo)dicopper(II) complexes supported by the tridentate ligand, efficient oxygenation of phenolates to the corresponding catechols has been accomplished to provide a good model reaction of tyrosinase. The bis(μ-oxo)dicopper(III) complexes, on the other hand, undergo aliphatic ligand hydroxylation as well as oxygen atom transfer to sulfides to give the corresponding sulfoxides. In the reaction of bis(μ-oxo)dicopper(III) complex with 10-methyl-9, 10-dihydroacridine (AcrH_2) and 1, 4-cyclohexadiene (CHD), a new active oxygen intermediate such as a (μ-oxo)(μ-oxyl radical)dicopper(III) or a tetranuclear copper-oxygen complex has been suggested to be involved as the real active oxygen species for the C-H bond activation of the external substrates. A mixed valence bis(μ_3-oxo) trinuclear copper(II, II, III) complex has also been assessed using the didentate ligand with the smallest N-alkyl substituent (methyl). Mechanistic details of the above reactions as well as ligand effects on the copper(I)-dioxygen reactivity are discussed systematically. In addition to the copper-dioxygen complexes, a similar type of nickel-dioxygen complexes as well as copper-disulfide complexes have been developed in order to provide further insights into the redox functions of metalloproteins