立体ジフェニルカルベンの構造の決定は,in situ X線結晶学分析によって行われます
Masaki Kawano1, Katsuyuki Hirai, Hideo Tomioka
1Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo 152-8551, Japan. mkawano@appchem.t.u-tokyo.ac.jp
Journal of the American Chemical Society
|February 1, 2007
まとめ
ディフェニルジアゾメタンの結晶状態の光反応を調査したところ,トリプレートディフェニルカルベン (DPC) は,熱力学的安定性だけでなく,結晶包装の影響を受けた構造を採用していることが明らかになった. DPCにおけるステリック・コンゲージは,周囲のマトリックスが柔らかくなる時に,幾何学的なリラックスにつながります.
科学分野:
- フォトケミストリーは,写真化学です.
- 固体化学 固体化学
- クリスタログラフィーです.
- オーガニック・ケミストリー オーガニック・ケミストリー
背景:
- ディフェニルディアゾメタン (diphenyldiazomethanes) は,ディフェニルカルベン (DPCs) の前駆体であり,様々な環境で研究されている反応性中間物質である.
- 以前,ガラスのマトリックスを使った研究で,DPC構造に関するスペクトロスコピカルデータが得られた.
- DPCの幾何学に対する固体状態の影響を理解することは,光反応の制御に不可欠です.
研究 の 目的:
- 置換されたディフェニルディアゾメタンの一連の結晶状態の光反応を調査する.
- 結晶状態の光誘導トリプレートDPCの構造と溶液またはガラスマトリックスで得られた構造を比較する.
- DPCの幾何学と安定性に対する結晶包装とステリック効果の役割を明らかにする.
主な方法:
- ディフェニルジアゾメタンとその光誘発DPCの結晶構造を決定するためのインシットX線結晶学.
- 分子特性を探査するための光譜技術 (ESRなど)
- 理論的な計算 (例えば,潜在エネルギー表面分析) を行って,エネルギー景観を理解する.
主要な成果:
- bis(2,4,6-トリクロロフェニル) ディアゾメタン,bis(2,4,6-トリブロモフェニル) ディアゾメタン,およびbis(2,6-ジブロモ-4-テート-ブチルフェニル) ディアゾメタンから派生したトリプレートDPCの結晶構造を決定した.
- 結晶状態の構造と,以前にガラスマトリックスで報告された構造の間で,重要な違いが観察されました.
- トリペットDPCは結晶状態において微妙な構造的変化を示したが,C(:) -Ar結合の長さは例外で,ステリカルに阻害されたケースでは著しく短かった.
- クリスタルパッキングは,DPC構造に大きく影響し,いくつかの化合物のパッキングは同一で,他の化合物のパターンは異なる.
- ESRの研究は,結合角度と比較して,インタープラナー角度でのより大きな柔軟性を示しました.
結論:
- クリスタルパッキング効果は,固体状態のトリプルDPCの幾何学を決定する上で重要な役割を果たします.
- 立体的に混雑した三重体DPCは,前体構造によって,形状的に固いマトリックスに閉じ込められるが,マトリックスが柔らかくなった時にリラックスする.
- 観察された構造的差異は,DPCのような反応性中間物質の安定化における周囲環境の重要性を強調しています.
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