オルガンニッケル・ラジカル・コンプレクスのリガンド・レドックス・アクティビティは幾何学によって制御される
Gregory A Dawson1, Qiao Lin1, Michelle C Neary2
1Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States.
Journal of the American Chemical Society
|September 11, 2023
まとめ
研究者はニッケル基複合体を合成し特徴づけました 彼らは4座標複合体のN-リガンドがリドックス活性であり,3座標複合体とは異なり,リガンド中心のラジカルを形成することを発見した.
科学分野:
- 有機金属化学
- カタリシス
- ラジカル・ケミストリー
背景:
- ニッケル触媒はクロスカップリング反応に不可欠であり,しばしばバイデントのN-リガンドを用いてラジカル経路を可能にします.
- オルガンニッケル・ラジカル・コンプレックスはこれらの触媒サイクルにおける中間物質として提案されているが,その電子構造は完全に理解されていない.
研究 の 目的:
- バイデントのN-リガンド (bpy,phen,pyrox) に支えられたオルガンニッケル基複合体を合成し,特徴づけること.
- これらのニッケル・ラジカル・コンプレクスの電子構造の経験的規則を確立する.
- カタリシス中のニッケルラジカル中間物質の安定化におけるN-リガンドの役割を明らかにする.
主な方法:
- オルガンニッケル基複合体の一連の合成と特徴付け.
- 電子構造を決定するスペクトル学と電気化学の研究.
- 四座標 (正方形) と三座標 (三角形) の複合体の比較分析
主要な成果:
- ニッケル・ラジカル・コンプレクスの電子構造の経験的規則を確立した.
- 4座標複合体のN-リガンドの酸化還元活性が観察され,リガンド中心のラジカルが生じる.
- 3座標複合体ではリガンドリオックス活性が見つからず,これはニッケル中心のラジカルとして記述される.
結論:
- N-リガンドの還酸化活動は,ニッケル基複合体の調整幾何学に依存する.
- リガンド・レドックス活性が,ラジカルの性質に影響する (リガンド中心対ニッケル中心).
- ニッケルラジカルを安定させる中間物質に関する洞察は,クロスカップリングのための最適化ニッケル触媒の開発に役立ちます.
関連する概念動画
02:57Coordination Number and Geometry
15.9K
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.
15.9K
02:51Metal-Ligand Bonds
20.9K
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...
20.9K
02:42Valence Bond Theory
8.7K
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...
8.7K
03:02Colors and Magnetism
11.8K
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...
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...
11.8K
02:34Structural Isomerism
19.3K
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...
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...
19.3K