非古典的三角形 (TPB) Co-H2複合体における自由H2回転対ジャーン=テラー制約
William A Gunderson1, Daniel L M Suess, Henry Fong
1Department of Chemistry, Northwestern University , Evanston, Illinois 60208-3113, United States.
Journal of the American Chemical Society
|September 23, 2014
まとめ
コバルトヒドリド複合体の陽子交換は,局所化を示す鉄ヒドリド複合体とは異なり,回転によって発生します. この違いは,分子対称性と回転障壁に影響を与える異なる電子構造と振動結合によるものです.
科学分野:
- 無機化学 無機化学とは
- 量子化学とは,量子化学である.
- スペクトロスコーピーは,スペクトロスコーピーを用います.
背景:
- 金属水化物複合体における陽子交換は,化学反応性を理解する上で極めて重要です.
- Jahn-Teller (JT) - 活性状態とビブロン結合は,分子行動に大きく影響する.
- コバルト (Co-H2) と鉄 (Fe-H2) の水素複合体を比較すると,電子構造効果の洞察が得られます.
研究 の 目的:
- (TPB) Co(H2) (Co-H2) の回転によるプロトン交換のメカニズムを調査する.
- Co-H2 の H2 の動態を,以前に研究された Fe-H2.2 と比較する.
- H2ダイナミクスにおける電子構造と振動結合の役割を明らかにする.
主な方法:
- 電子パラマグネティック共振 (EPR) と電子核二重共振 (ENDOR) のスペクトロスコーピー.
- クリスタル構造の決定のための中性子 difraktion.
- 分子動力学の1次元のローター問題の分析.
主要な成果:
- Co-H2は,C3対称性とH2交換から生じる支配的な6倍回転障壁により,2KでロータのようなH2の振る舞いを表しています.
- Fe-H2は,Fe(3d)→H2(σ*) πバックリンクと二次的なJT歪みによる支配的な2倍バリアにより,2KでのH2の局所化を示しています.
- ENDORのスペクトロスコピーは,Co-H2とFe-H2.2の固有結合特性と超精密結合を明らかにしています.
結論:
- H2は,Co-H2軸の周りを回転し,量子統計学的要件によって支配されるため,Co-H2に陽子交換をします.
- Co-H2 と Fe-H2 の異なる回転障壁は,電子構造,振動結合,分子対称性の変化に起因する.
- この研究は,ヒドリド複合体における金属-リガンド相互作用の探査におけるENDORスペクトロスコピーの感度を強調しています.
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