金属複合体のリン酸ダイエステルの水解の変更されたメカニズム
Tim Humphry1, Marcello Forconi, Nicholas H Williams
1Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA.
Journal of the American Chemical Society
|December 12, 2002
まとめ
二核コバルト複合体は,新しい添加除去機構を介してメチルp-ニトロフェニルフォスファートの水解を劇的に加速します. 動的同位体効果は,速度制限のステップで,複雑でないダイスターとは異なる,重要なP-O結合分裂を明らかにします.
科学分野:
- 無機化学 無機化学とは
- 反応メカニズム 反応メカニズム
- バイオミメティック・ケミストリー
背景:
- リン酸二酸化エステルの水解は,生物学的システムにおいて極めて重要です.
- 二核金属複合体は,酵素活性部位を模倣することができる.
- 反応機構の理解は,触媒の設計に役立ちます.
研究 の 目的:
- 二核コバルト複合体へのメチルp-ニトロフェニルリン酸複合体の水解機構を解明する.
- 水解反応の移行状態を調査する.
- 複雑でないダイスターとメカニズムを比較する.
主な方法:
- 水解の運動学的研究.
- 酸素 (18O) と窒素 (15N) のイソトープを用いた運動イソトープ効果 (KIEs) の測定.
- 複合型と非複合型ダイステルの水解速度の比較.
主要な成果:
- 複合性のダイステルは,複合性の無いダイステルよりも約10^11倍速く水解した.
- 橋渡しヒドロキシド核フィルの大きな逆18O KIEは,前期的な速度決定段階の核愛性攻撃を示した.
- ニトロフェニル脱出群の18Oおよび15N KIEの大部分は,速度決定のステップで重要なP-Oエステル結合分裂を示した.
結論:
- 複合型ダイステルの水解は,加法除去機構を経由して進行し,複合型ダイステルの協調メカニズムとは異なる.
- 速度制限のステップは,p-ニトロフェニル脱出基を中間物質から排出することを含む.
- 複雑なダイステル水解の移行状態は,広範囲のP-O結合分裂を示します.
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