スピンクロスオーバー特性に関する電子制御
Francesca Milocco1, Folkert de Vries1, Imke M A Bartels1
1Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Journal of the American Chemical Society
|November 16, 2020
まとめ
研究者らは,調節可能なスピン・クロスオーバー行動を示すホルマザナートリガンドを持つ新しい鉄 (II) 複合体を開発した. これらの化合物は,低スピン状態と高スピン状態を切り替えることで,材料科学と触媒の応用の可能性を示しています.
科学分野:
- 協調化学
- 材料科学
- スピン・クロスオーバー現象
背景:
- dブロック金属複合体のスピン状態の移行は,構造,反応性,および情報貯蔵やメタロ酵素触媒などのアプリケーションに不可欠です.
- スピンクロスオーバー化合物は,通常,八面体環境における協調的に飽和した金属中心に限られる.低協調性のスピンクロスオーバー複合体は稀である.
- ステリックおよび電子効果によるリガンドフィールド強度 (ΔO) の調節は,スピンクロスオーバー材料の設計における重要な戦略である.
研究 の 目的:
- フォーマザナートリガンドを含む四座標 (擬似) 四面体鉄 (II) 複合体を合成し,特徴づけること.
- 溶液中の熱誘導スピンクロスオーバーの変調 (S=0からS=2) を電子置換効果を用いて調べる.
- 固体状態のパッキング効果がスピン・クロスオーバーの行動に及ぼす影響を調査する.
主な方法:
- 6つの鉄 (II) 複合体の合成,様々な形式のリガンド.
- 溶液ベースのスピンクロスオーバー試験,温度依存測定 (T1/2) を含む.
- X線結晶学による固体構造分析
- スピンクロスオーバー熱力学と電子効果を理解するための密度関数理論 (DFT) の計算.
主要な成果:
- 合成された6つの鉄 (II) 複合体すべては,室温 (300368 K) 以上の移行温度 (T1/2) の溶液でスピンクロスオーバーを示す.
- X線結晶学では,ほとんどの複合体は固体状態で低スピンですが,パッキング効果は厳格な高スピンまたは漸進的なスピンクロスオーバー行動につながる可能性があります.
- DFT計算では,フォームザナートリガンドのπ受容体特性により,低スピン状態の安定化が確認され",逆転した"リガンドフィールドと有意な金属リガンド共性が生じました.
結論:
- フォルマザナートリガンドの電子置換剤は,低座標鉄 (II) 複合体の溶液中のスピンクロスオーバー熱力学を効果的に調節する.
- 固体パッキング効果は,観察されたスピン状態とクロスオーバー行動に大きく影響し,時には固有の電子的好みを覆すことができます.
- この研究は,調節性特性を有する新しいスピンクロスオーバー材料の設計におけるフォームザナートリガンドの可能性を強調し,代替剤の配置 (C-Ar vs. N-Ar) は金属リガンド結合に異なった影響を及ぼします.
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