ミックス・バレンット・ダイアイロン・μ-カルビン・μ-ヒドリド・コンプレックス: 窒素酵素への影響
Charles H Arnett1, Isabel Bogacz2, Ruchira Chatterjee2
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Journal of the American Chemical Society
|September 25, 2020
まとめ
窒素酵素 FeMo-コファクター中間体は,二鉄μ-カルビネ複合体を使用してモデル化されました. レドックス化学は,窒素固定の多電子変換を促進するために重要な金属-リガンド共振性の変化を明らかにした.
科学分野:
- バイオ有機化学
- 有機金属化学
- 生物化学
背景:
- 窒素酵素FeMo-コファクター (FeMoco) は,4e-および4H+移転後にN2を結合する.
- この混合バレントの中間物質の構造と電子学は十分に理解されていません.
- パルス EPR 研究では,2つのFe- ((μ-H) -Fe分子が存在することを示唆している.
研究 の 目的:
- ナイロゲンゼのバイオオルガンメタリッククラスタを理解するために
- EPR活性Fe (μ-C) (μ-H) モデル複合体をスペクトル的に特徴付ける.
- μ-ヒドリドリガンドに対するバレンスの移位の影響を調査する.
主な方法:
- 二酸化鉄μ-カルビンの複合体の合成とリドックス操作.
- パルス電子パラマグネティック共振 (EPR) スペクトロスコーピー
- X線吸収スペクトロスコーピー,Fe Mössbauer研究,そしてDFT計算.
主要な成果:
- 窒素酵素E3およびE4状態に似ている2つのEPR活性Fe<μ-C) <μ-H>複合体が特徴付けられました.
- 両種とも低温でS = 1/2状態を示します.
- レドックス化学はFe-C共用性の有意な変化を誘導した (- 2e-減量で50%).
結論:
- FeMoco E4(4H) 状態のヒドリドリガンドは,イソヴァレンスの FeIIIセンターをブリッジする可能性がある.
- コヴァレンシーは金属の余剰電荷を ブリッジカーボンに再分配することで変化させます
- このメカニズムは,窒素固定に不可欠な多電子変換を容易にする.
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