鉄(IV) ケチミド複合体の合成と特徴付け
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
まとめ
研究者は,大量のリガンドで新しい鉄複合体を合成しました. 予期せぬことに,完全に酸化した鉄複合体Fe ((NC ((t)) Bu (((2)) ((4) は,その前駆体とは異なる二磁性基底状態と正方形の平面幾何学を示した.
科学分野:
- 有機金属化学 有機金属化学
- 協調化化学について
- 無機合成の無機合成とは
背景:
- 巨大なリガンドを持つ鉄複合体は,そのユニークな電子的および構造的性質のために興味があります.
- 低座標鉄種の反応性と電子構造を調査することは,基本的な化学的原理を理解するために不可欠です.
研究 の 目的:
- 大量のNC(t) Bu(2) リガンドを特徴とする新しい鉄複合体を合成し,特徴づけること.
- これらの鉄複合体の電子的および構造的特性に対する酸化状態と調整環境の影響を調査する.
主な方法:
- 鉄 (III) クロライドとリチウムビス (III) トートブチルアミドリガンドの反応.
- ヨウ素を用いた制御された酸化.
- X線結晶学と磁気感受性測定を用いた特徴付け.
主要な成果:
- 鉄 (((II) 複合体 [Li (((THF) ](2) [Fe (((NC (((t) Bu (((2)) ((4)) ] (1) と鉄 (((III) 複合体 [Li (((DME) ]][Fe (((NC (((t) Bu ((2)) ((4)) ] (2) の合成について
- 中性鉄 ((IV) 複合体Fe ((NC ((t) Bu ((2)) ((4) (3) をさらに酸化することによって合成する.
- 複合体1と2は高スピン,四面体幾何学を示し,複合体3は二磁性,正方形の平面幾何学を示しています.
結論:
- 大量のNC(t) Bu(2) リガンドは,低協調性の鉄種を安定させる.
- 酸化は,四面体から正方形平面幾何学への移行,高スピンから二磁性状態への移行を含む,重要な構造的および電子的な変化につながります.
関連する概念動画
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...