Increase of Direct C-C Coupling Reaction Yield by Identifying Structural and Electronic Properties of High-Spin Iron Tetra-azamacrocyclic Complexes.
Increase of Direct C-C Coupling Reaction Yield by Identifying Structural and Electronic Properties of High-Spin Iron Tetra-azamacrocyclic Complexes.
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DOI：
10.1021/acs.inorgchem.8b00777
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发表时间：
2018-08-06
影响因子：
4.6
通讯作者：
Green KN
中科院分区：
文献类型：
--
作者：
Brewer SM;Wilson KR;Jones DG;Reinheimer EW;Archibald SJ;Prior TJ;Ayala MA;Foster AL;Hubin TJ;Green KN
大环配体作为过渡金属催化剂的骨架已经被广泛地研究，用于氧和氢原子转移反应。使用与大环配体结合的地球丰富的金属促进的C-C反应尚未被很好地理解，但可能是替代目前最常用于这些方法的昂贵且有毒的贵金属体系的绿色替代物。因此，八种高自旋铁配合物促进了苯基硼酸和吡咯的Suzuki-Miyaura C-C直接偶联生成2-苯基吡咯的产率（[Fe 3 +L1（Cl）2]+、[Fe 3 +L4（Cl）2]+、[Fe 2 +L5（Cl）]+、[Fe 2 +L6（Cl）2]、[Fe 3 +L7（Cl）2]+、[Fe 3 +L8（Cl）2]+、[Fe 2 +L9（Cl）]+，和[Fe ~（2+）L_（10）（Cl）]~+），以确定结构和电子性质对催化效率的影响。具体地，比较催化剂络合物以评价五种性质对催化剂反应产率的影响：1.催化剂的配位要求，2.每个复合物的氧化还原半电位，3。拓扑约束/刚性，4. N原子修饰增加复合物的氧化稳定性，以及5.几何参数当使用含有五齿配体的络合物代替具有四齿配体的络合物时，观察到催化反应产率降低42%，基于这一点确认了对两个不稳定的顺式配位位点的需要。还观察到铁（III/II）氧化还原电位与催化反应产率之间的强相关性，其中[Fe 2 + L 6（Cl）2]提供最高产率（81%，−405 mV）。氧化还原电位与产率的洛伦兹拟合预测，这些催化剂可以进行更精细的调整，以进一步提高产率。有趣的是，探索的其余性质并没有显示出与催化反应产率的直接、强烈的关系。总之，这些结果表明，使用无机配位化学的基本概念对配体骨架的修饰可用于通过控制铁中心的氧化还原化学来控制大环铁络合物的催化活性。此外，这些数据为设计用于该反应的改进催化剂和理解配体支架对其他反应的催化活性的影响的策略提供了方向。
Macrocyclic ligands have been explored extensively as scaffolds for transition metal catalysts for oxygen and hydrogen atom transfer reactions. C-C reactions facilitated using earth abundant metals bound to macrocyclic ligands have not been well-understood but could be a green alternative to replacing the current expensive and toxic precious metal systems most commonly used for these processes. Therefore, the yields from direct Suzuki-Miyaura C-C coupling of phenylboronic acid and pyrrole to produce 2-phenylpyrrole facilitated by eight high-spin iron complexes ([Fe3+L1(Cl)2]+, [Fe3+L4(Cl)2]+, [Fe2+L5(Cl)]+, [Fe2+L6(Cl)2], [Fe3+L7(Cl)2]+, [Fe3+L8(Cl)2]+, [Fe2+L9(Cl)]+, and [Fe2+L10(Cl)]+) were compared to identify the effect of structural and electronic properties on catalytic efficiency. Specifically, catalyst complexes were compared to evaluate the effect of five properties on catalyst reaction yields: 1. the coordination requirements of the catalyst, 2. Redox half-potential of each complex, 3. topological constraint/rigidity, 4. N-atom modification(s) increasing oxidative stability of the complex, and 5. geometric parameters. The need for two labile cis-coordination sites was confirmed based on a 42% decrease in catalytic reaction yield observed when complexes containing penta-dentate ligands were used in place of complexes with tetra-dentate ligands. A strong correlation between iron(III/II) redox potential and catalytic reaction yields was also observed, with [Fe2+L6(Cl)2] providing the highest yield (81%, −405 mV). A Lorentzian fitting of redox potential versus yields predicts that these catalysts can undergo more fine tuning to further increase yields. Interestingly, the remaining properties explored did not show a direct, strong relationship to catalytic reaction yields. Altogether, these results show that modifications to the ligand scaffold using fundamental concepts of inorganic coordination chemistry can be used to control the catalytic activity of macrocyclic iron complexes by controlling redox chemistry of the iron center. Furthermore, the data provides direction for the design of improved catalysts for this reaction and strategies to understand the impact of a ligand scaffolds on catalytic activity of other reactions.
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影响因子：
56.9
作者：
Chen, Mark S.;White, M. Christina
通讯作者：
White, M. Christina
DOI：
10.1007/3418_2015_99
发表时间：
2015-01-01
期刊：
IRON CATALYSIS II
影响因子：
--
作者：
Bedford, Robin B.;Brenner, Peter B.
通讯作者：
Brenner, Peter B.
DOI：
10.1039/dt9840001349
发表时间：
1984-01-01
期刊：
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
影响因子：
--
作者：
ADDISON, AW;RAO, TN;VERSCHOOR, GC
通讯作者：
VERSCHOOR, GC
影响因子：
15
作者：
Chow, Toby Wai-Shan;Wong, Ella Lai-Ming;Che, Chi-Ming
通讯作者：
Che, Chi-Ming
影响因子：
2.6
作者：
Agata, Ryosuke;Iwamoto, Takahiro;Nakamura, Masaharu
通讯作者：
Nakamura, Masaharu