[12]アヌレンのモビウス芳香度:トウィストカップリング結合シフトによるシス・トランス・イソメリゼーション
Claire Castro1, William L Karney, Miguel A Valencia
1Department of Chemistry, University of San Francisco, California 94117, USA. castroc@usfca.edu
Journal of the American Chemical Society
|July 7, 2005
まとめ
[12]アヌレンの容易な熱的構成の変化は,トウィストカップルの結合シフトメカニズムによって起こります. このプロセスは,典型的なアンヌレンのメカニズムとは異なる,Möbiusトポロジーを持つ非常に芳香的移行状態を伴う.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 理論化学 理論化学について
- コンピューティング・ケミストリー
背景:
- アヌレンは,単一結合と二重結合を交互に持つ循環性炭化水素である.
- アヌレンのダイナミックなプロセスと構造変化を理解することは,その反応性と性質を予測するために極めて重要です.
- 以前の研究では,構造の変化を無効にするための平面結合シフトメカニズムをしばしば想定していた.
研究 の 目的:
- [12]annuleneの容易な熱的構成変化のメカニズムを解明するために.
- [12]アヌレンのイソメリゼーションに関与する移行状態の性質を調査する.
- 提案されたメカニズムと,アサイクリックポリエネおよび他のアンヌレネで観察されたメカニズムを比較する.
主な方法:
- 密度関数理論 (DFT) の計算.密度関数理論 (DFT) の計算.密度関数理論 (DFT) の計算.密度関数理論 (DFT) の計算.密度関数理論 (DFT) の計算.密度関数理論 (DFT) の計算.密度関数理論 (DFT) の計算.
- クープレッド・クラスター (CC) の計算,具体的には CCSD ((T) /cc-pVDZ//BH&HLYP/6-311+G**.
- イソメリゼーション経路における移行状態の識別と特徴付け.
主要な成果:
- [12]annulene.の熱的構成の変化に対して,トウィストカップルの結合シフトメカニズムが特定されました.
- このプロセスの移行状態は,高芳香度とMöbiusトポロジーを示しています.
- tri-trans-[12]annuleneのdi-trans同位体に対する18.0 kcal/molの計算された同位体化バリアは,実験データとよく一致しています.
- 他の [12]アンヌレンのコンフォマーについて,2つの追加の芳香的なモビウス結合シフト移行状態が発見されました.
結論:
- 中性 [4n] アヌレンの動的過程には中性モビウス芳香アヌレンが含まれる.
- 特定されたメカニズムは,無効性における平面結合シフトの長年の仮定に異議を唱える.
- この研究は,アンヌレンの構造動態におけるモビウス芳香性の重要な役割の証拠を提供します.
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