Weakly Coupled Biologically Relevant Cu2II(μ-η1:η1-O2) cis-Peroxo Adduct that Binds Side-On to Additional Metal Ions
Weakly Coupled Biologically Relevant Cu2II(μ-η1:η1-O2) cis-Peroxo Adduct that Binds Side-On to Additional Metal Ions
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DOI：
10.1021/ja5025047
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发表时间：
2014-05-21
影响因子：
15
通讯作者：
Meyer, Franc
中科院分区：
文献类型：
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作者：
Dalle, Kristian E.;Gruene, Tim;Meyer, Franc
许多铜金属酶活化O2并将其转移到有机底物的能力在文献中引起了广泛的关注。对合成类似物的研究提供了对潜在中间体结构的详细了解，从而有助于指导机理研究。我们在此报告的晶体学特征的合成Cu-2（II）（μ-η（1）：η（1）-O-2）的复杂表现出顺式过氧键的几何形状，已知的铁化学，但以前没有观察到的铜。通过紫外-可见光谱、共振拉曼光谱和红外光谱的详细研究提供了铜-氧相互作用显著减弱的证据（λ =约3000 M-1 cm（-1），nu（Cu-O）= 437 cm（-1），nu（O-O）= 799 cm（-1）），相对于已知的“偶联”Cu 2 O2物质，这与磁性测量结果一致，磁性测量结果表明过氧化物仅介导弱反铁磁耦合（-2J = 144 cm（-1））。这些特征与计算预测的O2与3型铜中心结合的过渡态的特征相当，为所提出的O-2活化机制提供了实验证据，并支持Cu-2（II）（μ-eta（1）：eta（1）-O-2）顺式物质的生物相关性。过氧化物键的排列也允许钠阳离子的结合，在固态和溶液中都可以观察到。结合诱导电子水平上的变化，如通过UV-vis光谱法（K-a = 1700 M-1）监测的，这让人想起铁-氧物种的氧化还原非活性金属结合。所呈现的结果突出了这些活性氧物种经历的类似化学，关于它们的形成机制和它们参与的分子相互作用。
The ability of many copper metalloenzymes to activate 02 and transfer it to organic substrates has motivated extensive attention in the literature. Investigations focusing on synthetic analogues have provided a detailed understanding of the structures of potential intermediates, thereby helping to guide mechanistic studies. We report herein a crystallographically characterized synthetic Cu-2(II)(mu-eta(1):eta(1)-O-2) complex exhibiting cis-peroxo bonding geometry, known in iron chemistry but previously unobserved for copper. Detailed investigation by UV-vis, resonance Raman, and infrared spectroscopies provides evidence for a significantly diminished copper-oxygen interaction (epsilon approximate to 3000 M-1 cm(-1), nu(Cu-O) = 437 cm(-1), nu(O-O) = 799 cm(-1)) relative to those in known 'coupled' Cu2O2 species, consistent with magnetic measurements which show that the peroxide mediates only weak antiferromagnetic coupling (-2J = 144 cm(-1)). These characteristics are comparable with those of a computationally predicted transition state for 02 binding to type 3 copper centers, providing experimental evidence for the proposed mechanism of O-2 activation and supporting the biological relevance of the Cu-2(II)(mu-eta(1):eta(1)-O-2) cis-species. The peroxide bonding arrangement also allows binding of sodium cations, observed both in the solid state and in solution. Binding induces changes on an electronic level, as monitored by UV-vis spectroscopy (K-a = 1700 M-1), reminiscent of redox-inactive metal binding by iron-oxygen species. The results presented highlight the analogous chemistry these reactive oxygen species undergo, with respect to both their mechanism of formation, and the molecular interactions in which they participate.