Heme-copper-dioxygen complexes: toward understanding ligand-environmental effects on the coordination geometry, electronic structure, and reactivity.
Heme-copper-dioxygen complexes: toward understanding ligand-environmental effects on the coordination geometry, electronic structure, and reactivity.
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DOI：
10.1021/ic9020993
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发表时间：
2010-04-19
影响因子：
4.6
通讯作者：
Karlin, Kenneth D.
中科院分区：
文献类型：
--
作者：
Halime, Zakaria;Kieber-Emmons, Matthew T.;Qayyum, Munzarin F.;Mondal, Biplab;Gandhi, Thirumanavelan;Puiu, Simona C.;Chufan, Eduardo E.;Sarjeant, Amy A. N.;Hodgson, Keith O.;Hedman, Britt;Solomon, Edward I.;Karlin, Kenneth D.
配体的性质是配位化学中控制结构和反应性的一个重要方面。在我们的研究血红素/铜/氧的反应性相关的细胞色素c氧化酶O2还原化学，我们比较了两个高自旋血红素过氧铜[FeIII-O22-CuII]+配合物的分子和电子结构含有N4-四齿（1）或N3-三齿（2）铜配体。结合先前报道的和新的共振拉曼和EXAFS数据耦合到DFT计算，我们报告的几何结构和更完整的电子描述的高自旋血红素过氧铜配合物1和2，建立μ-（O22-）侧上的Fe III和端上的Cu II（μ-η2：η1）结合的配合物1，但侧上/侧上（μ-η2：η2）μ-过氧配合物2。比较和总结了这两种配合物对CO、PPh 3、酸和酚类的反应活性的异同。通过对一个新的μ-氧代配合物2a的X射线结构与先前报道的1a的X射线结构（2和1的两个热分解产物）的比较，发现两个μ-氧代配合物的Fe-O-Cu角有很大的不同（1a中的α Fe-O-Cu = 178.2°，2a中的α Fe-O-Cu = 149.5°）。2与一当量的外源N-供体轴向碱基的反应导致形成独特的低温稳定的低自旋血红素-O2-Cu络合物（2b），但在相同条件下，向1添加轴向碱基导致血红素-过氧-Cu组装体的解离和O2的释放。2b与酚类反应，夺取氢原子（e- + H+），导致O-O键断裂，形成高价铁基[Fe IV =O]配合物（2c）。2C的性质被证实通过比较其光谱特征和反应性与那些独立制备的铁基复合物。由氢原子提取产生的苯氧基自由基1）使用产生稳定自由基的酚通过EPR光谱直接检测，或2）通过检测两个苯氧基自由基的偶联产物间接检测。
The nature of the ligand is an important aspect of controlling structure and reactivity in coordination chemistry. In connection with our study of heme/copper/oxygen reactivity relevant to cytochrome c oxidase O2-reduction chemistry, we compare the molecular and electronic structure of two high-spin heme-peroxo-copper [FeIII-O22--CuII]+ complexes containing N4-tetradentate (1) or N3-tridentate (2) copper ligands. Combining previously reported and new resonance Raman and EXAFS data coupled to DFT calculations we report a geometric structure and more complete electronic description of the high-spin heme-peroxo-copper complexes 1 and 2, which establish μ-(O22-) side-on to the FeIII and end-on to CuII (μ-η2:η1) binding for the complex 1 but side-on/side-on (μ-η2:η2) μ-peroxo coordination for the complex 2. We also compare and summarize the differences and similarities of these two complexes in their reactivity toward CO, PPh3, acid and phenols. The comparison of a new X-ray structure of μ-oxo complex 2a with the previously reported 1a X-ray structure, two thermal decomposition products respectively of 2 and 1, reveals a considerable difference in the Fe-O-Cu angle between the two μ-oxo complexes (∠Fe-O-Cu = 178.2° in 1a, ∠Fe-O-Cu = 149.5° in 2a). The reaction of 2 with one equivalent of exogenous N-donor axial base leads to the formation of a distinctive low-temperature stable, low-spin heme-O2-Cu complex (2b), but under the same conditions the addition of an axial base to 1 leads to the dissociation of the heme-peroxo-Cu assembly and the release of O2. 2b reacts with phenols performing hydrogen-atom (e– + H+) abstraction resulting in O-O bond cleavage and the formation of high-valent ferryl [FeIV=O] complex (2c). The nature of 2c was confirmed by comparison of its spectroscopic features and reactivity with those of an independently prepared ferryl complex. The phenoxyl radical generated by the hydrogen-atom abstraction was either 1) directly detected by EPR spectroscopy using phenols that produce stable radicals or 2) indirectly by detection of the coupling product of two phenoxyl radicals.
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影响因子：
15
作者：
Fox, S;Nanthakumar, A;Blackburn, NJ
通讯作者：
Blackburn, NJ
影响因子：
3.9
作者：
Blomberg, LM;Blomberg, MRA;Siegbahn, PEM
通讯作者：
Siegbahn, PEM
影响因子：
56.9
作者：
Collman, James P.;Devaraj, Neal K.;Chidsey, Christopher E. D.
通讯作者：
Chidsey, Christopher E. D.
影响因子：
4.9
作者：
Collman, James P.;Decreau, Richard A.;Sunderland, Christopher J.
通讯作者：
Sunderland, Christopher J.
影响因子：
4.6
作者：
Collman, JP
通讯作者：
Collman, JP