Fast O2 binding at dicopper complexes containing Schiff-base dinucleating ligands
Fast O2 binding at dicopper complexes containing Schiff-base dinucleating ligands
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DOI：
10.1021/ic0701108
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发表时间：
2007-06-11
影响因子：
4.6
通讯作者：
Costas, Miquel
中科院分区：
文献类型：
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作者：
Company, Anna;Gomez, Laura;Costas, Miquel
制备了一类新的二铜(I)配合物[(Cu2L)- l -I-L-R](X)(2) (R = H, 1X, R = Bu-t， 2X和R = NO2, 3X, X = CF3SO3, ClO4, SbF6，或BArF， BArF) [B{3,5-(CF3)(2) c6h4](-))，其中L-R是一种希夫碱配体，含有两个三齿结合位点，由一个木基间隔剂连接，并对其与O-2的反应进行了研究。这些复合物的设计目的是再现3型铜蛋白活性位点的结构方面；它们含有两个三坐标铜位点和一个相当灵活的豆荚配体主链。通过单晶x射线衍射分析，确定了1ClO(4)、2CF(3)、SO(3)、2ClO(4)和3BArF中心点CH3CN的固态结构。1ClO(4)在固态下为聚合物结构，2CF(3)SO(3)、2ClO(4)和3BArF、CH3CN为单体。用H-1和F-19核磁共振谱在溶液中对配合物进行了研究，发现存在动力学过程。丙酮中的1-BArF和1-3CF(3)SO(3)与O2快速反应，分别生成亚稳定的[Cu-III (2)(α - o)(2)(L-R)](2+) 1-3（O-2）和[Cu-2(III)(mu-O)(2)(CF3SO3)(L-R)](+) 1-3(O-2)（CF3SO3）物质，用紫外可见光谱和共振拉曼分析对其进行表征。相反，1-3BArF在CH2Cl2中与O-2反应导致分子间O-2结合。用DFT方法研究了O-2加合物的化学性质和结构参数，以及Cu-2(III)(mu-O)(2)形式相对于Cu-2(II)(mu-eta（2): eta(2)-O-2）异构体的相对稳定性。用停流UV-vis研究了1X， X = CF3SO3和BArF在丙酮中与O-2的反应，反应速率(k)为3.82(4)× 10(3) M-1 s(-1)， δ H双匕首= 4.9 +/- 0.5 kJ中心点k -1中心点mol(-1)， δ s双匕首= -148 +/- 5 J中心点k -1中心点mol(-1))，比母体[Cu-2(I)(m-XYLMeAN)]（2+）快近3个数量级。热分解1-3（O-2）不会产生芳香羟基化。讨论了O-2与1X (X) CF3SO3和BArF)结合的机制和动力学，并与报道的O-2加工铜蛋白模型相关的例子进行了比较。铜离子在O-2结合和活化中的协同作用从这一分析中清楚地确立了。
A new family of dicopper (I) complexes [(Cu2L)-L-I-L-R](X)(2) (R = H, 1X, R = Bu-t, 2X and R = NO2, 3X, X = CF3SO3, ClO4, SbF6, or BArF, BArF) [B{3,5-(CF3)(2)C6H3 4](-)), where L-R is a Schiff-base ligand containing two tridentate binding sites linked by a xylyl spacer, has been prepared and characterized, and its reaction with O-2 has been studied. The complexes were designed with the aim of reproducing structural aspects of the active site of type 3 dicopper proteins; they contain two three-coordinate copper sites and a rather flexible podand ligand backbone. The solid-state structures of 1ClO(4), 2CF(3)SO(3), 2ClO(4), and 3BArF center dot CH3CN have been established by single-crystal X-ray diffraction analysis. 1ClO(4) adopts a polymeric structure in the solid state while 2CF(3)SO(3), 2ClO(4), and 3BArF, CH3CN are monomeric. The complexes have been studied in solution by means of H-1 and F-19 NMR spectroscopy, which put forward the presence of dynamic processes. 1-BArF and 1-3CF(3)SO(3) in acetone react rapidly with O2 to generate metaestable [Cu-III (2)(alpha-O)(2)(L-R)](2+) 1-3(O-2) and [Cu-2(III)(mu-O)(2)(CF3SO3)(L-R)](+) 1-3(O-2)(CF3SO3) species, respectively, that have been characterized by UV-vis spectroscopy and resonance Raman analysis. Instead, reaction of 1-3BArF with O-2 in CH2Cl2 results in intermolecular O-2 binding. DFT methods have been used to study the chemical identities and structural parameters of the O-2 adducts, and the relative stability of the Cu-2(III)(mu-O)(2) form with respect to the Cu-2(II)(mu-eta(2): eta(2)-O-2) isomer. The reaction of 1X, X = CF3SO3 and BArF, with O-2 in acetone has been studied by stopped-flow UV-vis exhibiting an unexpected very fast reaction rate (k) 3.82(4) x 10(3) M-1 s(-1), Delta H double dagger = 4.9 +/- 0.5 kJ center dot mol(-1), Delta S double dagger = -148 +/- 5 J center dot K-1 center dot mol(-1)), nearly 3 orders of magnitude faster than in the parent [Cu-2(I)(m-XYLMeAN)](2+). Thermal decomposition of 1-3(O-2) does not result in aromatic hydroxylation. The mechanism and kinetics of O-2 binding to 1X (X) CF3SO3 and BArF) are discussed and compared with those associated with selected examples of reported models of O-2-processing copper proteins. A synergistic role of the copper ions in O-2 binding and activation is clearly established from this analysis.