三坐标铜 (I) 胺基和氨基基基复合物
Neal P Mankad1, William E Antholine, Robert K Szilagyi
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|March 4, 2009
概括
一种新型的铜复合体模仿了蓝色铜蛋白与快速电子转移. 氧化形式是铜(I) - 氨基基,而不是铜(II) - 胺基,具有独特的反应性.
科学领域:
- 协调化学 协调化学
- 生物有机化学 生物有机化学
- 有机金属化学 有机金属化学
背景情况:
- 蓝铜蛋白是重要的金属酶,具有独特的1型活性位点.
- 了解它们的电子结构是模仿它们功能的关键.
- 具有特定连接体的铜复合体可以模拟这些活性位点.
研究的目的:
- 合成和描述一个三坐标铜复合体作为1型蓝铜蛋白的功能模型.
- 为了研究氧化铜复合物的电子结构.
- 探索其独特电子配置产生的反应性.
主要方法:
- 在Cu (I) 和Cu (II) 氧化状态下的铜复合物的隔离和结构性表征.
- 测量自我交换电子转移反应速率.
- 多边的X射线吸收光谱 (XAS) 和多频电子磁共振 (EPR).
- 密度函数理论 (DFT) 的计算.
主要成果:
- 一个三坐标Cu-NR(2) 系统成功合成和表征.
- 该系统表现出高的自我交换电子转移速率常数 (k(S) >= 10(7) M(-1) s(-1)).
- 谱学和计算分析显示氧化形式是Cu (I) - 氨基基,NR (II) 单元上约70%的未配对电子,而不是Cu (II) - 氨基基物种.
结论:
- 合成的铜复合体作为1型蓝铜蛋白活性站点的功能模型.
- 氧化物种具有不寻常的电子结构,最好的描述是Cu (I) -氨基基基.
- 这种独特的电子配置使新的反应性成为可能,包括原子转移和C-C合反应.
相关概念视频
Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Coordination Number and Geometry
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.
Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
Coordination Compounds and Nomenclature
In most main group element compounds, the valence electrons of the isolated atoms combine to form chemical bonds that satisfy the octet rule. For instance, the four valence electrons of carbon overlap with electrons from four hydrogen atoms to form CH4. The one valence electron leaves sodium and adds to the seven valence electrons of chlorine to form the ionic formula unit NaCl (Figure 1a). Transition metals do not normally bond in this fashion. They primarily form coordinate covalent bonds, a...
Formation of Complex Ions
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...


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