移転水素化触媒によるO(2) の水素化のメカニズム調査
Sugata Chowdhury1, Fahmi Himo, Nino Russo
1Dipartimento di Chimica, Università della Calabria, I-87030, Arcavacata di Rende, Italy.
Journal of the American Chemical Society
|March 12, 2010
まとめ
この研究では,ハイブリッド密度関数計算を使用して分子酸素の水素化を調査しています. ゆっくりとしたステップは,Ir-H結合へのO2挿入であり,酸性条件は,この触媒サイクルのためのエネルギー性を改善します.
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
- カタリシス カタリシス カタリシス
背景:
- 分子酸素の触媒性水素化は,様々な化学プロセスにおいて極めて重要です.
- Cp*IrH(TsDPEN) (1H(H) のようなイリジウム複合体は,この反応の触媒として知られています.
- 反応メカニズムを理解することは,触媒効率を最適化するための鍵です.
研究 の 目的:
- Cp*IrH(TsDPENによって触媒化された分子酸素水素化のメカニズム的な詳細を解明する.
- ハイブリッド密度関数計算を用いて,触媒サイクルを探求する.
- 反応経路とエネルギー学に対する酸性条件の影響を調査する.
主な方法:
- ハイブリッド密度関数計算 (B3LYP) を用いて,潜在エネルギー表面を研究した.
- 触媒 (1) の水素化過程とその対応するイリジウム (((III) アミンカチオン ([1H] (((+)) を分析した.
- 計算分析を行い,レートを決定するステップと中間を特定しました.
主要な成果:
- ダイミド複合体 (1) にH(2) を加えることは好ましいが,ゆっくりであり,ブロンステッド酸によって加速される.
- O(2) 還元は,イリジウムヒドロペロキソ中間体経由で行われ,O(2) がIr-H結合に挿入され,ゆっくりとしたステップとなる.
- 酸性条件では,反応エネルギーが強化され,H(2) O(2) 中間物質を通過し,陽子化された触媒 [1H](+) を再生します.
結論:
- 計算結果は,反応動力学と中間物質に関する実験的観測と一致しています.
- この研究では,Ir-H結合へのO(2) 挿入を,触媒サイクルにおける速度制限ステップとして特定しています.
- 酸性条件は,分子酸素の水素化に,よりエネルギー的に有利な経路を提供します.
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