決して存在しなかったコバルト水化物:シュラウザーの"ヒドリドコバルキシム"を再考
David C Lacy1, Gerri M Roberts1, Jonas C Peters1
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Journal of the American Chemical Society
|March 24, 2015
まとめ
再調査されたコバルト複合体は,以前はヒドリドと考えられていたが,実際にはコバルト (II) 種である. この発見は,コバロキシメスを用いた水素進化反応 (HER) のメカニズム研究に影響を与えています.
科学分野:
- 無機化学 無機化学とは
- エレクトロカタリシス.
- 水素進化反応 (HER) とは
背景:
- コバルト-ジメチルグリオキシム (dmg) 複合体は,HER研究における重要な電気触媒である.
- シュラウザーの想定されたコバルト水化物複合体の分離は,H.E.R.におけるCo (III) -H中間物質のサポートを提供した.
- このいわゆる水素は,コバルキシム水素とHER触媒に関する研究で広く引用されています.
研究 の 目的:
- シュラウザーのフォスフィン安定化コバルト-dmg複合体の構造を再評価する.
- 水素進化反応 (HER) メカニズムに関連する種のアイデンティティを明確にする.
- 陽子NMR信号の誤った帰属をヒドリド種に訂正するために.
主な方法:
- 固体構造を決定するX線結晶学.
- プロトンのNMRを含むスペクトル解析.
- 合成されたコバルト-dmg複合体と不純物の特徴.
主要な成果:
- 以前はコバルト (III) 水化物として識別された複合体は,コバルト (II) 複合体, [Co (II) (dmgH) 2P (nBu) 3] として再割り当てされます.
- このコバルト (II) 複合体は,固体状態で二酸化し,サポートされていないCo-Co結合を形成します.
- 誤ってヒドリドとして割り当てられたパラマグネティック不純物は, -5.06 ppmで陽子NMR信号を発現します.
結論:
- 広く引用されている"ヒドリドコバルキシム"は,ヒドリドではなく,コバルト (II) 複合体である.
- この構造的再配置は,コバロキシメスによって触媒化された水素進化反応 (HER) のメカニズムを理解するために重要である.
- この発見は,この特定のコバルトヒドリドの存在を前提とした以前のメカニズムモデルを再評価することを必要としています.
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