Fast O2 Binding at Dicopper Complexes Containing Schiff-Base Dinucleating Ligands
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- 作者：Anna Company ; Laura Gó ; mez ; Rubé ; n Mas-Ballesté ; Ivan V. Korendovych ; Xavi Ribas ; Albert Poater ; Teodor Parella ; Xavier Fontrodona ; Jordi Benet-Buchholz ; Miquel Solà ; Lawrenc
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：June 11, 2007
- 年：2007
- 卷：46
- 期：12
- 页码：4997 - 5012
- 全文大小：340K
- 年卷期：v.46,no.12(June 11, 2007)
- ISSN：1520-510X
文摘
A new family of dicopper(I) complexes [CuI2RL](X)2 (R = H, 1X, R = tBu, 2X and R = NO2, 3X, X = CF3SO3,ClO4, SbF6, or BArF, BArF = [B{3,5-(CF3)2C6H3}4]-), where RL is a Schiff-base ligand containing two tridentatebinding sites linked by a xylyl spacer, has been prepared and characterized, and its reaction with O2 has beenstudied. The complexes were designed with the aim of reproducing structural aspects of the active site of type 3dicopper proteins; they contain two three-coordinate copper sites and a rather flexible podand ligand backbone.The solid-state structures of 1ClO4, 2CF3SO3, 2ClO4, and 3BArF·CH3CN have been established by single-crystalX-ray diffraction analysis. 1ClO4 adopts a polymeric structure in the solid state while 2CF3SO3, 2ClO4, and 3BArF·CH3CN are monomeric. The complexes have been studied in solution by means of 1H and 19F NMR spectroscopy,which put forward the presence of dynamic processes. 1-3BArF and 1-3CF3SO3 in acetone react rapidly with O2to generate metaestable [CuIII2(
-O)2(RL)]2+ 1-3(O2) and [CuIII2(-O)2(CF3SO3)(RL)]+ 1-3(O2)(CF3SO3) species,respectively, that have been characterized by UV-vis spectroscopy and resonance Raman analysis. Instead, reactionof 1-3BArF with O2 in CH2Cl2 results in intermolecular O2 binding. DFT methods have been used to study thechemical identities and structural parameters of the O2 adducts, and the relative stability of the CuIII2(-O)2 formwith respect to the CuII2(-
2:2-O2) isomer. The reaction of 1X, X = CF3SO3 and BArF, with O2 in acetone hasbeen studied by stopped-flow UV-vis exhibiting an unexpected very fast reaction rate (k = 3.82(4) × 103 M-1 s-1,
H
= 4.9 ± 0.5 kJ·mol-1, S = -148 ± 5 J·K-1·mol-1), nearly 3 orders of magnitude faster than in the parent[CuI2(m-XYLMeAN)]2+. Thermal decomposition of 1-3(O2) does not result in aromatic hydroxylation. The mechanismand kinetics of O2 binding to 1X (X = CF3SO3 and BArF) are discussed and compared with those associated withselected examples of reported models of O2-processing copper proteins. A synergistic role of the copper ions inO2 binding and activation is clearly established from this analysis.
-O)2(RL)]2+ 1-3(O2) and [CuIII2(-O)2(CF3SO3)(RL)]+ 1-3(O2)(CF3SO3) species,respectively, that have been characterized by UV-vis spectroscopy and resonance Raman analysis. Instead, reactionof 1-3BArF with O2 in CH2Cl2 results in intermolecular O2 binding. DFT methods have been used to study thechemical identities and structural parameters of the O2 adducts, and the relative stability of the CuIII2(-O)2 formwith respect to the CuII2(-2:2-O2) isomer. The reaction of 1X, X = CF3SO3 and BArF, with O2 in acetone hasbeen studied by stopped-flow UV-vis exhibiting an unexpected very fast reaction rate (k = 3.82(4) × 103 M-1 s-1,H = 4.9 ± 0.5 kJ·mol-1, S = -148 ± 5 J·K-1·mol-1), nearly 3 orders of magnitude faster than in the parent[CuI2(m-XYLMeAN)]2+. Thermal decomposition of 1-3(O2) does not result in aromatic hydroxylation. The mechanismand kinetics of O2 binding to 1X (X = CF3SO3 and BArF) are discussed and compared with those associated withselected examples of reported models of O2-processing copper proteins. A synergistic role of the copper ions inO2 binding and activation is clearly established from this analysis.