コバルトにおける多電子移転:フェニラゾピリジンリガンドの影響
Kate M Waldie1, Srinivasan Ramakrishnan1, Sung-Kwan Kim1
1Department of Chemistry, Stanford University , Stanford, California 94305, United States.
Journal of the American Chemical Society
|March 7, 2017
まとめ
フェニラゾピリジンの新しいコバルト複合体は,軽い電位で珍しい2電子の減少を経験します. この発見により,効率的な2電子変換のための単核移行金属複合体の開発が進んでいます.
科学分野:
- 有機金属化学
- 電気化学
- 無機化学
背景:
- 単核第一列の移行金属複合体は,触媒作用において極めて重要です.
- 軽い電位で多電子還酸化プロセスを達成することは依然として重要な課題です.
- フェニラゾピリジンリガンドは,酸化還元調節のためのユニークな電子特性を提供します.
研究 の 目的:
- コバルト-フェニラゾピリジン複合体の電気化学的振る舞いを調査する
- 軽い電位で2電子の減少を達成する可能性を探求する.
- 観察された酸化還元作用を制御する構造的および電子的要因を解明する.
主な方法:
- 複合体の電気化学的性質を研究するために,周期的な電圧測定法が使用されました.
- コバルトセンの化学的還元により,還元された種を分離した.
- X線結晶学,光譜学,密度関数理論 (DFT) の計算が特徴付けに使用された.
主要な成果:
- ディカチオン複合体 [CpCo (azpy) (CH3CN) ] (ClO4) 2 (1) は,−0.16 V で Fc0/+ に対して2電子の可逆的減少を示した.
- これは,連続した1電子減少を示す類似のビピリジンおよびピラゾリルピリジン複合体と対照的である.
- 単離された二重縮小複合体 [CpCo ((azpy)) ] (2) は空気に安定し,二磁性であった.
- DFTの計算は,2電子の減少と構造再構成と金属-リガンドの軌道重複を相関させた.
結論:
- フェニラゾピリジンリガンドは,コバルト複合体におけるユニークな2電子還元経路を促進する.
- コバルトd軌道とアゾーπ*軌道が重なり合っていることが,観測された潜在的な逆転の鍵となる.
- この研究は,軽い電位,多電子還酸化反応のための単核複合体の開発に向けた重要なステップを表しています.
さらに関連する動画
![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
関連する概念動画
03:02Colors and Magnetism
14.4K
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...
14.4K
02:42Valence Bond Theory
11.4K
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...
11.4K
02:58Crystal Field Theory - Octahedral Complexes
31.4K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
31.4K
02:51Metal-Ligand Bonds
25.1K
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...
25.1K
02:34Structural Isomerism
22.3K
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...
22.3K
![[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12422.jpg&w=3840&q=75)
01:21[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
3.5K
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.
3.5K