铁胺复合物的合成和表征 (IV)
Richard A Lewis1, Guang Wu, Trevor W Hayton
1Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA.
Journal of the American Chemical Society
|August 26, 2010
概括
研究人员用重的配体合成了新的铁复合物. 意想不到的是,完全氧化的铁复合体Fe ((NC ((t) Bu ((2)) ((4) 显示出二磁性基态和方形平面几何,与其前身不同.
科学领域:
- 有机金属化学 有机金属化学
- 协调化学 协调化学
- 无机合成 无机合成
背景情况:
- 铁复合物与重的配体具有独特的电子和结构性质,因此有兴趣.
- 探索低坐标铁物种的反应性和电子结构对于理解基本化学原理至关重要.
研究的目的:
- 合成和描述具有重NC(t) Bu(2) 连接体的新型铁复合体.
- 研究氧化状态和协调环境对这些铁复合物的电子和结构性质的影响.
主要方法:
- 铁 (II) 化物与 (bis) (tert-butyl) 胺联体的反应.
- 使用进行受控的氧化.
- 使用X射线晶体学和磁感应度测量的表征.
主要成果:
- 合成的铁(II) 复合物[Li(THF) ](2) [Fe(NC(t) Bu(2)) ((4) ] (1) 和铁(III) 复合物[Li(DME) ]][Fe(NC(t) Bu(2)) ((4) ] (2).
- 通过进一步的氧化合成中性铁 (IV) 复合物Fe (NC) (t) Bu (b) (c) (d)) (3) 的合成.
- 综合体1和2呈现高旋转,四面体几何形状,而综合体3呈现二磁性,方形平面几何形状.
结论:
- 庞大的NC(t) Bu(2) 连接体稳定了低坐标的铁物种.
- 氧化导致显著的结构和电子变化,包括从四面体过渡到正方形平面几何和高旋转到二磁性状态.
相关概念视频
03:45Formation 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...
01:09Complexation Equilibria: Factors Influencing Stability of Complexes
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:34Structural 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...
00:39Complexometric Titration: Overview
Complexometric titration involves the formation of a complex by reacting a metal ion with one or more ligands. A visual indicator often detects the end point of a complexometric titration. It is added to the metal solution before the titration, forming a stable metal–indicator complex and imparting color to the solution. As the titration approaches the equivalence point, the excess of the added ligand displaces the indicator from the metal–indicator complex, releasing the free indicator. The...
01:23Complexation Equilibria: Overview
Complexation reactions take place when dative or coordinate covalent bonds form between metal ions and ligands. The compounds formed in these reactions are called coordination compounds. The number of bonds formed between the metal ion and the ligands is called its coordination number. Generally, most metal ions in an aqueous solution are solvated by water molecules and thus exist as aqua complexes.
The equilibrium constant of the complexation reaction is represented as the formation constant...
The equilibrium constant of the complexation reaction is represented as the formation constant...