カチオン性,中性,アニオン性ビス ((イミノ)) ピリジンの鉄アルキル複合体の合成と電子構造:単一成分エチレンポリメリゼーション触媒における還酸化活性評価
Aaron M Tondreau1, Carsten Milsmann, Andrew D Patrick
1Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
Journal of the American Chemical Society
|October 2, 2010
まとめ
研究者らは,鉄アルキル複合体をビス・イミノ・ピリジンリガンドで合成した. 彼らは,リガンドの電子特性の変化とアルキル群の位置づけが,鉄の中心を調節できることを発見しました.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
- 材料科学 材料科学とは
背景:
- ビス・イミノ・ピリジン鉄アルキル複合体は,エチレンポリメリゼーションの単一成分触媒として知られています.
- これらの複合体の電子構造を理解することは,触媒活動の最適化に不可欠です.
研究 の 目的:
- カチオン性,中性,アニオン性ビス (((イミノ)) ピリジンの鉄アルキル複合体を調製し,特徴づけること.
- これらの複合体の電子構造と分子構造を,様々なスペクトロスコピーと difraktion テクニックを用いて確立する.
- 電子構造とオレフィンポリメリゼーション触媒の関連性を相関させる.
主な方法:
- カチオン性,中性,アニオン性ビス (((イミノ)) ピリジンの鉄アルキル複合物の合成.
- 分子構造の決定のためのX線 difraktion.
- 電子構造分析のためのモースバウアー光譜と磁気化学.
- 計算上の洞察のためのオープンシェル密度関数理論 (DFT) 計算.
主要な成果:
- カチオンの複合体は,中性で,リドックス無毒のビス・イミノ・ピリジン結合体を持つ高スピンの鉄性 (S(Fe) = 2) である.
- 一電子還元により,高スピンの鉄イオンと反鉄磁性結合したビス・イミノ・ピリジン基離子を持つ中性アルキルが得られる.
- アニオン複合体へのさらなる還元により,閉殻ビス・イミノ・ピリジンダイアニオンを持つ低スピンの鉄中心 (S・Fe) = 0) が生成され,リガンドベースの還元とスピン状態の変化が示されます.
結論:
- ビス・イミノ・ピリジンの鉄アルキル複合体の電子構造は,還元とリガンド改変によって調整できます.
- リガンドフィールドの強さとアルキルリガンドの位置の変化は,鉄の中心におけるスピン状態の変化を誘導する.
- これらの発見は,これらの鉄複合体によるオレフィンポリメリゼーション触媒のメカニズムに関する根本的な洞察を提供します.
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