キューバンのタイプのCo4S4クラスター:合成,リドックスシリーズ,磁気基底状態
Liang Deng1, Eckhard Bill, Karl Wieghardt
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Journal of the American Chemical Society
|September 3, 2009
まとめ
この研究では,新しいコバルト-硫黄のクラスター, [Co(4) S(4) PPr ((i) ((3)) ((4)) ]と [Co(4) S(4) ((Pr(i) ((2) NHCMe ((2)) ((4)) ]を合成し,それらは窒素酵素の構造的な類似性を示しています. これらのコバルトクラスターは,独特の磁気特性と酸化還元反応性を表し,金属硫黄クラスターの既知の化学を拡張しています.
科学分野:
- 無機化学 無機化学とは
- バイオ・オーガニック化学 バイオ・オーガニック化学
- マテリアルサイエンス 材料科学
背景:
- アゾトバクター・ヴィネランディ・ニートロゲンゼの鉄タンパク質には,窒素固定に不可欠な[Fe ((4) S ((4)) ]クラスターが含まれています.
- カーベンのクラスター [Fe(4) S(4) (((Pr(i) 2) NHCMe(2)) ((4) ] (9) は,還元された窒素酵素鉄タンパク質の既知の構造的および電子的なアナログである.
- 他の移行金属,特にコバルトとの類似したクラスターの存在と性質は,ほとんど未調査のままである.
研究 の 目的:
- 窒素酵素酸鉄タンパク質に類似した新しいコバルト-硫黄のクラスタを合成し,特徴づけること.
- これらの新しいコバルトクラスターの構造,電子,磁気特性を調査する.
- これらの金属硫黄系における酸化還元反応とリガンド効果を探求する.
主な方法:
- コバルト-硫黄のクラスターの合成は,特定の前駆体システム (CoCl2 / Pr2 / P3 / Me3 / Si2 / S / THF) を使用しています.
- リンガンド交換反応により,カルベン置換コバルトのクラスターを形成する.
- カチオンの種を分離するために化学的酸化.
- 構造的,電子的,および酸化還元性特性を決定するためのスペクトル顕微鏡および電気化学的方法.
主要な成果:
- [Co}4S}4Pr}3Pr}4Pr}3と[Co}4S}4Pr}2NHCMe}2Pr}4Pr}5の合成が成功しました.
- クラスター3〜6は,鉄の類型に似たキューバ型幾何学を示し,酸化還元系をサポートしています.
- 中性クラスター3と5は,コバルト (II) イオンのスピンカップリングから生じるS=3基底状態を有しています.
- カーベンのリガンドは,フォスフィンのリガンドよりも強い電子ドナーとして識別されています.
- ロンブ・ブリッジド・ノンキューバン (RBNC) 構造を持つ八核コバルト-硫黄のクラスターを副産物として分離した.
結論:
- コバルト-硫黄のクラスターは,窒素化鉄のクラスターの構造と電子特性を効果的に真似することができます.
- これらのクラスターのスピン状態と磁気特性は,リガンドの選択と金属の酸化状態の影響を受けます.
- この研究は,鉄以外の既知の[M(4) S(4) L(4) ](z) クラスタの範囲を拡大し,生物無機および材料化学の研究のための新しい道を開きます.
- ロンブ・ブリッジド・ノン・キューバン (RBNC) とエッジ・ブリッジド・ダブル・キューバン (EBDC) の構造を相互変換するための概念モデルが提案されています.
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