Pd媒介による分子酸素の活性化: Pd(0) と直接挿入との比較
Jason M Keith1, William A Goddard, Jonas Oxgaard
1Materials Process and Simulation Center, MC (139-74), California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|August 7, 2007
まとめ
この研究は,分子酸素とパラジウム水化物複合体の反応機構を明らかにし,Pd(0) と直接挿入による経路を明らかにしています. 環境に害のない化学開発には直接挿入が望ましい.
科学分野:
- カタリシス カタリシス カタリシス
- 有機金属化学 有機金属化学
- グリーン・ケミストリー (Green Chemistry)
背景:
- 環境に害のない化学物質の開発には,ダイオキシゲンの直接使用が必要です.
- ダイオキシゲンを用いた直接的酸化は,しばしば非実用的で,機械的理解を必要とします.
- パラジウムヒドリド複合体は,触媒サイクルにおける重要な中間物質である.
研究 の 目的:
- トロウレン溶解パラジウム水化物複合体による分子酸素の反応機構を解明する.
- Pd(0) を経由する経路に焦点を当て,直接挿入と比較する.
- パラジウム水素の分子酸素による再酸化経路の完全なマッピングを提供します.
主な方法:
- 量子力学の計算 (PBF溶媒モデルを使ったB3LYP/LACVP**).
- 塩基の存在下でPd (II-) (Sparteine) (H) (Cl) を調べました.
- スピンの移行と反応の完了の分析.
主要な成果:
- 最低バリアのPd(0) 経路を特定し,塩基補助デプロトネーション,O2結合,塩化物損失を含む.
- エタ(2) - ペロキソ - パラジウム複合体の形成を特徴づけた.
- 特定された直接挿入経路は,研究されたシステムにとって好ましい (DeltaDeltaH++ = 6.2 kcal/mol,DeltaDeltaG++ = 7.5 kcal/mol).
結論:
- スパルテインの二重性およびパイ受容リガンドの欠如は,直接挿入を好みます.
- これらのメカニズムの理解は,ダイオキシゲンによる実際の直接酸化の開発に役立ちます.
- 経路の優先順位を切り替えるための提案が提供されています.
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