[CpRu (((PhCCAr)) (((dppe)) ]+でアルキンから非置換ヴィニリデンの内部イソメリゼーションに関するDFT研究
Miho Otsuka1, Noriko Tsuchida, Yousuke Ikeda
1Department of Chemistry and Biochemistry, Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan.
Journal of the American Chemical Society
|September 21, 2012
まとめ
ルテニウム複合体は,直接の1,2シフトメカニズムを通じて,内部アルキーンからビニリデンの同体化を経験する. 電子を寄与するアリル基が少ないと,典型的な核愛性反応とは対照的に,移動が好ましい.
科学分野:
- 有機金属化学 有機金属化学
- コンピューティング・ケミストリー
- 反応メカニズム研究 反応メカニズム研究
背景:
- ルテニウム複合体の内部アルキン-ヴィニリデン同体化の調査は,有機金属反応経路の理解に不可欠です.
- アリル置換剤やフォスフィンなどのリガンドの電子およびステリック効果は,反応機構に大きな影響を及ぼします.
- 精密な計算モデリングは,移行金属化学における複雑な反応ダイナミクスの解明に不可欠です.
研究 の 目的:
- 特定のルテニウム複合体における内部アルキン-ヴィニリデンイソメリゼーションメカニズムを計算的方法を用いて調査する.
- アリル置換剤 (R = OMe,Cl,CO2Et) が同化経路と活性化エネルギーに及ぼす影響を決定する.
- 移行状態における1,2シフトと移行の好みを支配する電子的要因を分析する.
主な方法:
- 量子力学と分子力学 (QM/MM) の組み合わせを用いた方法,特にONIOM (((B3PW91:UFF)).
- 反応メカニズムを分析するために,B3PW91機能の密度関数理論 (DFT) 計算を使用しました.
- 重要な電子効果を捉えるために,異なるQM領域を持つ3つの異なるモデルシステム (I-III) を調査しました.
主要な成果:
- イソメリゼーションは,すべての研究されたルテニウム複合体の直接の1,2シフトメカニズムによって進行します.
- トランジション状態におけるアルキーン・リガンドの指向の変化を含む経路3は,最もエネルギー的に有利な経路として特定されました.
- 計算された活性化エネルギーは,OMe,CO2Et,Cl置換複合体のそれぞれ13.7,15.0,16.4 kcal/molであった.
結論:
- アリル1,2シフトは核愛反応として特徴付けられ,ドナー-受容体分析が重要な洞察を提供している.
- 電子ドナー置換剤は,移行状態において,移住するアリル基ではなく,受け入れる炭素に陽性電荷を安定させる.
- 一般的な核好性反応とは対照的に,より少ない電子提供アリル基は,この特定のルテニウム触媒による異体化において,移住の利点を示します.
関連する概念動画
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Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...
Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...
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UV–Visible absorption spectra of conjugated dienes arise from the lowest energy π → π* transitions. The light-absorbing part of the molecule is called the chromophore, and the substituents directly attached to the chromophore are called auxochromes. A strong correlation exists between the absorption maxima, λmax, and the structure of a conjugated π system. The Woodward–Fieser rules predict the value of λmax for a given structure by adding the contributions...
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