カチオンのハフニウムシリル複合体と,Si-HとC-H結合によるシグマ結合メタテシス過程におけるその強化反応性
1Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, USA.
Journal of the American Chemical Society
|August 2, 2003
まとめ
この研究では,ボロン化合物と反応するハフニウムシリル複合体を調査しています. 研究者らは,ズウィテリオン性およびカチオン性ハフニウムシリル複合体の形成を観察し,シグマ結合転移およびC-H活性化反応におけるそれらの安定性と反応性を詳細に説明しました.
科学分野:
- 有機金属化学 有機金属化学
- メイングループ 化学
- カタリシス カタリシス カタリシス
背景:
- 初期の移行金属のオルガノシリル複合体は,触媒作用において極めて重要です.
- B ((C6F5) 3) のようなルイス酸とのハフニウムシリル複合体の反応性は完全に理解されていません.
- これらの反応の理解は,C-H活性化とシラン変換のための新しい触媒経路につながる可能性があります.
研究 の 目的:
- 混合リングおよびbis (cyclopentadienyl) ハフニウムシリルメチル複合体のB (C6F5) との反応を調査する3.
- その結果生じるズウィテリオンおよびカチオンのハフニウムシリル複合体を特徴づける.
- シグマ結合メタテシスおよびC-H活性化反応におけるこれらの複合体の反応性を調査する.
主な方法:
- ハフニウムシリルメチル複合体の合成と特徴付け.
- ハフニウム複合体の反応とトリス・ペンタフローロフェニル・ボラン (B・C6F5) 3).
- 構造的決定のための光譜分析 (NMR) とX線結晶学.
- イソトープ効果測定を含む反応機構を明らかにするための運動学的研究.
主要な成果:
- CpCp*Hf[Si(SiMe3) 3) Me.Me.から,安定したズウィトリオンハフニウムシリル複合体 [CpCp*HfSi(SiMe3) [3] [MeB(C6F5) 3 ] の形成.
- Cp2Hf (((SiR3) Me前駆体からカチオニウムハフニウムシリル複合体の合成.
- Cp2Hf ((SitBuPh2) ((mu-Me) B ((C6F5) 3) の分離と特徴づけ,その構造と特性を明らかにした.
- Mes2SiH2とのシグマ結合メタテシスの観察,HSitBuPh2とα-アゴスティックSi-H相互作用を持つ反応性種を生成する.
- ベンゼンとトルーエンのC-H結合活性化によるアリルおよびベンジルハフニウム複合体の形成の実証.
- C-H結合の活性化のための協調された移行状態メカニズムをサポートする運動データ.
結論:
- ハフニウムシリル複合体は,B ((C6F5) 3) と異なる反応性を示すため,ズウィテリオンとカチオンの両方の種を産生する.
- カチオンのハフニウムシリル複合体は,シグマ結合の転移とC−H結合の活性化を行うことができる.
- C-Hの活性化メカニズムは,動的および同位体証拠によって支持されるように,協調された移行状態を経由して進行します.
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