ポリフルオックスメタラートフレームワーク内で安定したMn (IV) とMn (V) -Hydroxo種による反応性とO2形成
Roy E Schreiber1, Hagai Cohen2, Gregory Leitus2
1†Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
Journal of the American Chemical Society
|June 13, 2015
まとめ
ポリフルオックスメタラート中のマンガン-オクソクラスターは,電子移転において反応性を示しているが,酸素原子の寄贈は弱い. Mn(IV) -OH-PFOMを特定のカチオンと結合すると,O2の形成が加速され,水酸化のための四分子中間物質が示唆されます.
科学分野:
- 無機化学 無機化学とは
- 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:
- マンガネス-オキソおよびヒドロキソ複合体は,酸素化および水の酸化において重要な役割を果たし,しばしば酵素を模倣する.
- 酵素ミミックは厳しい条件下で分解することができ,安定した無機酸化物クラスターの研究を動機付けます.
- オキシード環境における反応性中間物質の理解は,実用的な応用にとって極めて重要です.
研究 の 目的:
- manganese-substituted polyfluoroxometalates (PFOMs) を様々な manganese 酸化状態 (II-V) で合成し,特徴づけること.
- これらのマンガン-PFOM化合物の反応性,特にそれらの酸素原子献血および電子転送能力を調査する.
- 酸素進化のためのMn(IV) -hydroxo-PFOMの集積と反応性に対するアルカリ酸子の影響を調査する.
主な方法:
- マンガンが置換されたPFOMの一連の合成.
- 磁気感受性,X線光電子スペクトロスコーピー (XPS),X線吸収近辺構造 (XANES),拡張X線吸収微細構造 (EXAFS),電子顕微鏡,およびDOSY NMRを用いた特徴付け.
- 酸素原子移転および電子移転酸化を含む水における反応性研究,様々なアルカリカチオン添加物による.
主要な成果:
- 確認された酸化状態とリガンド環境 (aquaまたはhydroxo) を有するMn ((II,III,IV,V) -PFOM化合物の分離.
- Mn (((IV) -OH-PFOMとMn (((V) -OH-PFOMは酸素原子のドナーが弱いが,電子移転酸化には有効である.
- Cs+,Rb+,K+ (しかしLi+,Na+ではない) によって誘発されたMn(IV) -OH-PFOMの集積は,O2形成を加速し,四分子中介機構をサポートします.
結論:
- マンガン-PFOMは,酸化環境におけるマンガンの酸化状態と反応性を研究するための安定したプラットフォームを提供します.
- 観察された集積行動は,触媒活動におけるカチオン誘発構造変化の役割を強調しています.
- テトラ分子Mn ((IV) -ヒドロキソ中間体は,酸化物ベースのシステムにおけるO2形成の有効な経路として提案されています.
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