リガンド酸性定数方程式を用いて発見された移行金属ヒドリド複合体の電気化学的性質の系統的傾向
Benjamin E Rennie1, Renée G Eleftheriades1, Robert H Morris1
1Department of Chemistry, University of Toronto, 80 Saint George St., Toronto, Ontario M5S3H6, Canada.
Journal of the American Chemical Society
|September 17, 2020
まとめ
この研究は,パラマグネティック移行金属水化物複合体の酸度を推定する新しい方法を導入しています. この研究は,ヒドリドの安定性と酸化逆転性を予測することによって,触媒設計に関する洞察を提供します.
科学分野:
- 協調化学
- 有機金属化学
- カタリシス
背景:
- パラマグネティック移行金属水素の熱力学は,電気触媒と有機金属触媒の設計に不可欠です.
- ハイドリド複合熱力学を決定するための既存の方法は,特に豊富な3d金属には限られています.
研究 の 目的:
- アセトニトリル (MeCN) のパラマグネティック水素のpKaを,リガンド酸性定数 (LAC) の方程式を用いて初めて推定する.
- レドックスカップルの系統的な傾向を明らかにし,酸化されていない水素の結合解離自由エネルギー (BDFE ((MH)) を推定する.
- 水素酸化の電気化学的可能性を予測し,その可逆性を評価する.
主な方法:
- 200以上のヒドリド複合体のpKa値を推定するために,リガンド酸性定数 (LAC) の方程式を開発し,適用した.
- リドックス傾向を分析するために,文献の電気化学的ポテンシャルを使用した熱化学サイクルを使用した.
- 密度関数理論 (DFT) の計算を用いて,選択された水素の推定pKa値を検証した.
主要な成果:
- 200以上のパラマグネティック水素複合体のpKa ((LAC-MeCN) を成功裏に推定した.
- M (III/II),M (V/IV),M (II/I),Re (VI/V),Re (IV/III),M (IV/III) とM (II/I) の酸化還元カップルの体系的な傾向が明らかになった.
- pKa値と水素酸化の可逆性との間の相関が確立され,pKa < 0 は不可逆的酸化を示し,pKa > 0 は可逆的酸化を示します.
結論:
- LAC方程式は,パラマグネティック移行金属水素の熱力学を推定するための信頼できる方法を提供します.
- 推定されたpKa値とBDFE (MH) は,触媒の性能と安定性を予測するのに価値があります.
- pKaと酸化還元反応の関係を理解することは,効率的な電気触媒と有機金属触媒の設計の鍵です.
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