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μ-1,2-ペロキソとμ-1,1-ヒドロペロキソ二銅の,陽子誘導による可逆相互変換 (II) 複合体
Nicole Kindermann1, Sebastian Dechert1, Serhiy Demeshko1
1Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstraße 4, 37077 Göttingen, Germany.
Journal of the American Chemical Society
|June 11, 2015
まとめ
二銅 (II) ペロキソ複合体のプロトン化により,安定した水素ペロキソ複合体が得られます. この複合体は,X線 difraktionによって特徴付けられ,オクソ転送反応を媒介することができるが,水素原子抽象を媒介することはできません.
科学分野:
- 無機化学 無機化学とは
- 協調化化学について
- バイオ・オーガニック化学 バイオ・オーガニック化学
背景:
- 二銅 (II) 複合体とペロキソリガンドは,様々な酸化反応における重要な中間物質である.
- これらの複合体の反応性と安定性を理解することは,生物学的システムを模倣する鍵です.
- プロトネーション状態は,金属-ペロキソ種の電子的および構造的特性に大きな影響を与える.
研究 の 目的:
- μ-1,2-ペロキソ二銅 (II) 複合体のプロトネーションを調査する.
- 結果となるμ-1,1-ヒドロペロキソ二銅 (II) 複合体を特徴付ける.
- 酸化反応におけるヒドロペロキソ複合体の反応性を決定する.
主な方法:
- ピラゾラート基リガンドを用いたμ-1,2-ペロキソ二銅 (II) 複合体の合成と特徴付け.
- Cu2OOH単位のpKaを決定するためのプロトネーションとデプロトネーションの研究.
- ヒドロペロキソ複合体の構造的決定のためのX線 difraktion.
- O-O結合の振動を研究するために,光譜分析 (IR) を行う.
- PPh3を基質として使用した反応性研究.
主要な成果:
- μ-1,2-ペロプロキソ二銅 (II) 複合体 (2) のプロトン化により,安定した μ-1,1-ヒドロペロプロキソ二銅 (II) 複合体 (3) が得られます.
- Cu2OOH単位のpKaは,アセトニトリルで22.2 ± 0.3と決定されました.
- 複合体3は前例のない安定性 (t(1/2) = 9h) を示し,構造的に特徴づけられました.
- O-O結合の長さは同じままであったが,O-Oの伸縮頻度は複合体3で大幅に増加した.
- 複合体3は,PPh3への2e(-) オキソ移転を媒介するが,H原子抽象に対して反応しない.
結論:
- この研究では,二銅ペロキソ複合体の可逆性プロトネーション/デプロトネーションが示され,高いpKaは安定した水素ペロキソ種を示しています.
- 構造的およびスペクトル学的データは,陽子化時に微妙な,しかし重要な変化を明らかにします.
- ヒドロペロキソ二銅 (II) 複合体は,オクソ伝達反応の効果的な媒介であり,触媒における潜在力を強調しています.
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