Iron(II) complexes with amide-containing macrocycles as non-heme porphyrin analogues.
Iron(II) complexes with amide-containing macrocycles as non-heme porphyrin analogues.
复制标题
铁 (II) 与含酰胺大环化合物形成络合物作为非血红素卟啉类似物。
DOI：
10.1021/ic0701209
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发表时间：
2007
影响因子：
4.6
通讯作者：
Rybak-Akimova,ElenaV
中科院分区：
文献类型：
--
作者：
Korendovych,IvanV;Kryatova,OlgaP;Reiff,WilliamM;Rybak-Akimova,ElenaV
合成了大环五烯酸配体3,6,9,12,18-五氮杂环[12.3.1]十八烯-1(18),14,16-三烯-2,13-二酮（H2pydioneN5）和16-氯-3,6,9,12,18-五氮杂环[12.3.1]十八烯-1(18),14,16-三烯-2,13-二酮（H2pyCldioneN5）的铁（II）配合物，并对其进行了充分的表征。与H2pydione的一个或两个去质子酰胺基团的配合物都被分离出来。在前一种情况下，金属离子具有扭曲的八面体配位球；在后一种情况下，复合体采用五边形-双锥体的几何形状。核磁共振实验表明，该配体在二甲亚砜（DMSO）溶液中保持质子化状态。这些配合物即使在低温下也能保持高自旋态。铁（II）配合物的氧合动力学研究表明，配合物的去质子化状态对其与二氧的反应性有深远的影响。铁（II）的二去质子化配合物Fe（pydioneN5）在非质子溶剂中的氧化过程与铁（II）卟啉的氧化过程类似：通过铁（III）超氧和二铁（III）过氧，反应过程中的光谱变化证明了这一点，这在铁（II）配合物的浓度中是二阶的，并且反应速率与二氧浓度呈反比关系。氧化的最终产物是具有晶体学特征的铁(III) μ-氧二聚体。我们还发现，1-甲基咪唑的存在稳定了过氧二铁中间体。相同条件下，甲醇中Fe（pydioneN5）与二氧的反应有明显不同。该反应在铁（II）配合物和二氧中均为一级反应，光谱上未观察到中间产物。单去质子化配合物Fe(HpydioneN5)（Cl）也有类似的反应。来自溶剂（甲醇反应）或来自配合物本身(Fe（HpydioneN5)(Cl)）的可接近质子的存在足以改变这些大环系统中的氧化途径，这让人想起铁（II）卟啉配合物的性质。新的氨基吡啶大环可以被认为是“扩展卟啉类似物”家族的新成员。腔的膨胀提供了对自旋状态和质子可用性的控制。这些大环体系也允许容易的合成修饰，为新的，多功能金属配合物铺平道路。
Iron(II) complexes of macrocyclic pentadendate ligands 3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18),14,16-triene-2,13-dione (H2pydioneN5) and 16-chloro-3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18),14,16-triene-2,13-dione (H2pyCldioneN5) were synthesized and fully characterized. Complexes with one or two deprotonated amide groups of H2pydione were both isolated. In the former case the metal ion has a distorted octahedral coordination sphere; in the latter case the complex adopts a pentagonal−bipyramidal geometry. NMR experiments show that the protonation state of the ligand is preserved in a dimethyl sulfoxide (DMSO) solution. The complexes maintain a high-spin state even at low temperatures. Detailed kinetic studies of oxygenation of the iron(II) complexes showed that the deprotonation state of the complex has a profound effect on the reactivity with dioxygen. Oxygenation of the dideprotonated complex of iron(II), Fe(pydioneN5), in aprotic solvents proceeds via a path that is analogous to that of iron(II) porphyrins: via iron(III) superoxo and diiron(III) peroxo species, as evidenced by the spectral changes during the reaction, which is second-order in the concentration of the iron(II) complex, and with an inverse dependence of the reaction rate on the concentration of dioxygen. The final products of oxygenation are crystallographically characterized iron(III) μ-oxo dimers. We have also found that the presence of 1-methylimidazole stabilizes the diiron peroxo intermediate. The reaction of Fe(pydioneN5) with dioxygen in methanol is distinctly different under the same conditions. The reaction is first-order in both iron(II) complex and dioxygen, and no intermediate is spectroscopically observed. Similar behavior was observed for the monodeprotonated complex Fe(HpydioneN5)(Cl). The presence of an accessible proton either from the solvent (reactions in methanol) or from the complex itself (in Fe(HpydioneN5)(Cl)) proves sufficient to alter the oxygenation pathway in these macrocyclic systems, which is reminiscent of the properties of iron(II) porphyrin complexes. The new amidopyridine macrocycles can be considered as new members of the “expanded porphyrin analogue” family. The expansion of the cavity provides control over the spin state and availability of protons. These macrocyclic systems also allow for easy synthetic modifications, paving the way to new, versatile metal complexes.