カッパ-P,P,Si (biPSi) ピンサーリガンドを持つイリジウム化合物:不飽和複合体の反応性構造を好む
Eduardo Sola1, Alba García-Camprubí, José L Andrés
1Departamento de Química de Coordinación y Catálisis Homogénea, Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza, Spain. sola@unizar.es
Journal of the American Chemical Society
|June 15, 2010
まとめ
この研究では,イリジウム複合体を調査し,異なる調整行動と反応性を有する2つの同位体を示しました. これらの差異により,選択的挿入反応とポリメリゼーションが可能になり,イソメリゼーションは水素と潜在的なリガンドの影響を受けます.
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
- カタリシス カタリシス カタリシス
背景:
- 独特のカッパ-P,P,Si-Si ((Me) {(CH(2)) ((3) PPh ((2))) ((2)) リガンド (biPSi) を含む5座標のイリジウム複合体を研究した.
- これらの複合体は,アンチとシン同位体による均衡混合物として存在し,位置偏好はハロゲンと溶媒によって影響されます.
- 両方ともイソマーが歪んだ正方形のピラミッド構造を採用し,空白部位がシリコンに変換される.
研究 の 目的:
- これらのイリジウム複合体の構造,調整特性,挿入プロセス,動的振る舞いを明らかにする.
- アンチとシン同位体間の反応性の違いを理解するために.
- イソメリゼーションと挿入反応のメカニズムを探求する.
主な方法:
- イリジウム複合体の構造的特徴.
- アイソメアの均衡と反応を監視するための光譜研究 (NMR).
- 調整および挿入プロセスの運動および熱力学的分析.
- 機械論的提案を支援する計算研究 (MP2計算)
主要な成果:
- シン同位体では容易に6座標アダクトを形成するが,反同位体では調整が限られている.
- 挿入用反応剤は,シン同位体のIr-H結合と選択的に反応し,アルケニルまたはアルキル産物となる.
- アセチレンポリメリゼーションは,シン同位体の調整球の中で発生する.
- アンチイソマーは同化して合成製品になるが,その速度は挿入反応剤とH(2) 濃度に依存する.
- 提案されたイソメリゼーションメカニズムには,Ir(V) 中間物質とアゴスティック移行状態が含まれています.
結論:
- アンチとシン同位体間の構造的なニュアンスにより,調整と反応性において大きな違いが生じます.
- シン同位体は,選択的挿入反応とアセチレンポリメリゼーションに不可欠です.
- イソメリゼーション経路は外部要因の影響を受け,アゴスティック相互作用を含むメカニズムが提案されています.
さらに関連する動画
関連する概念動画
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...
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...
Radical Reactivity: Steric Effects
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic factors, steric factors also account...
Along with electronic factors, steric factors also account...
Radical Reactivity: Intramolecular vs Intermolecular
Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak carbon–halogen...
Pericyclic Reactions: Introduction
Pericyclic reactions are organic reactions that occur via a concerted mechanism without generating any intermediates. The reactions proceed through the movement of electrons in a closed loop to form a cyclic transition state, where rearrangement of the σ and π bonds yields specific products.
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic rearrangements are...
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic rearrangements are...
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
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.


