末端のCo (III) -Oxo複合体によるCH活性化におけるpKa-駆動の非同期性に関する実験的証拠
McKenna K Goetz1, John S Anderson1
1Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States.
Journal of the American Chemical Society
|February 12, 2019
まとめ
この研究では,C-H活性化におけるコバルト-オクソ複合体の反応性は,C-H結合強度ではなく,基板酸度 (pKa) によって導かれる. これは,移行金属オクソ複合体の新しい"非同期"の協調メカニズムを示唆しています.
科学分野:
- 有機金属化学
- 酸化化学
- キャタリシス
背景:
- 移行金属オクソ複合体によるC-H活性化は,生物学的および合成化学において極めて重要です.
- これらの複合体のメカニズムと反応パターンを理解することは,酸化化学の進歩に不可欠です.
研究 の 目的:
- 合成された遅い移行金属オクソ複合体,PhB ((tBuIm) 3CoIII OのC-H活性性を調査する.
- この複合体の反応性を支配する要因を特定し,特に基質pKaとC-H結合解離エネルギー (BDE) の影響を比較する.
主な方法:
- 複合体の結合体に対するpKaとO-H結合解離エネルギー (BDFE) の実験的決定.
- 9,10-ジヒドロアントラセンの反応の活性化パラメータの測定
- 様々な水素原子ドナーによる反応速度の評価
- C-H活性化メカニズムの実験と計算分析を組み合わせた.
主要な成果:
- PhB (tBuIm) 3CoIII Oの反応性は,確立されたパラダイムとは対照的に,主に基質のpKaに依存しています.
- 活性化パラメータを測定し,文献値と比較した.
- トランジション状態の分析は 陽子転移の特徴を明らかにした.
結論:
- このCoIII-oxo複合体のC-H活性化は,段階的なプロセスではなく,pKa駆動の非同期的な協調メカニズムによって行われます.
- この発見は,C−H活性化反応における代替選択性を可能とする,移行金属オクソ複合体の新しい反応パターンを提案する.
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