[CoIII(TAML) ]0/-複合体におけるリガンド・レドックス非無害性 窒素形成に影響する
Nicolaas P van Leest, Martijn A Tepaske, Jean-Pierre H Oudsen
1Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States.
Journal of the American Chemical Society
|December 18, 2019
まとめ
コバルト-TAML複合体におけるテトラアミドマクロサイクリックリガンド (TAML) のリドックス無毒性は確認された. この研究は,酸化コバルト-TAMLのリガンド中心のラジカルを明らかにし,触媒性ニートレンの転移反応に不可欠です.
科学分野:
- 無機化学
- 有機金属化学
- スペクトロスコーピー
- コンピュータ化学
背景:
- コバルト複合体におけるテトラアミドマクロサイクリックリガンド (TAML) スキャフォルドのリドックス反応は,2006年以来議論されてきた.
- リガンド・レドックス非無罪性を理解することは,触媒反応のメカニズムを解明するために重要である.
研究 の 目的:
- コバルト-TAML複合体におけるTAML骨幹のリドックス無毒性を明確に証明する.
- 酸化コバルト-TAML種の電子構造と,窒素移転反応におけるそれらの役割の特徴づけ.
主な方法:
- 特徴づけのために様々なスペクトロスコピック技術 (EPR,XANES,UV-vis) を利用した.
- 高解像度の質量スペクトロメトリーと磁気モメント測定を用いた.
- 電子構造を決定する多参照 (CASSCF) 計算を行いました.
主要な成果:
- アニオン性コバルト-TAML複合体のTAML骨幹は,一電子酸化時にリガンド中心のラジカルを形成し,無酸素であることが確認された.
- 酸化複合体の電子構造は,リガンド基と結合したS=1コバルト (III) センターから生じるダブルレット (S = 1/2) である.
- ニトロンの前駆体 (PhINN) との反応により,TAML中心の酸化が起こり,ニトロンの転移に不可欠なニトロン基複合体 ([Co(TAML) ((NNs)) と[Co(TAML)) ((NNs)) が形成される.
結論:
- コバルト複合体のTAMLリガンドは,有意な酸化還元非無罪性を示し,酸化還元活性成分として作用する.
- リガンド中心のラジカルは,これらのコバルト-TAML複合体によって媒介される触媒性ナイトレン伝達機構の重要な中間物質である.
- TAMLリガンドのリドックス状態は,モノまたはビスナイトレンの根幹複合体の形成を決定する.
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