ダイアザディエンリガンドを基にした安定した形式的にゼロバレンツと二磁性単価ニオビウムとタンタール複合体
P James Daff1, Michel Etienne, Bruno Donnadieu
1Laboratoire de Chimie de Coordination du CNRS, UPR 8241, 205 Route de Narbonne, 31077 Toulouse Cedex 4, France.
Journal of the American Chemical Society
|April 11, 2002
まとめ
この研究では,新しい反応を用いて,希少なゼロバルントのニオビウムとタンタール複合体を合成しています. これらの複合体は,リガンドに電子の移位により予期せぬ二磁性性を表し,従来の電子構造モデルに挑戦する.
科学分野:
- 有機金属化学 有機金属化学
- 無機化学 無機化学とは
- 協調化化学について
背景:
- 低価変種金属複合体の合成は,電子構造と反応性を理解するために重要である.
- ゼロバレンタル構成の偽オクターヘッドのニオビウムとタンタール複合体は希少で,ユニークな電子特性を備えています.
研究 の 目的:
- 新しく,形式的にゼロバレンツとモノバレンツの偽オクトヘッドラニオビウムとタンタール複合体を効率的に合成し,特徴づけること.
- これらの異常な複合体の電子構造と磁気特性を調査する.
主な方法:
- ナトリウム金属と1,4-ジソプロピル-1,4-ディアザ-1,3-ダイエン (iPr(2) -ダッド) を用いてニオビウムとタンタール複合体の合成.
- X線結晶学とスペクトロスコーピーを用いた特徴化.
- 密度関数理論 (DFT) を用いた計算分析.
主要な成果:
- Nb ((iPr ((2) -dad)) ((3) (52%の収量) と Ta ((iPr ((2) -dad)) ((3) (33%の収量) の効率的な合成である.
- 酸化時に二磁性単価複合体 [M(iPr(2) -dad) ((3) ]][BPh ((4) ] の形成.
- DFTの計算は,強力なt(2g) 軌道分裂を明らかにし,ダイアマグネチズムとリガンドの電子局所化につながった.
結論:
- 形式的にゼロヴァレンスの複合体は,アニオンリガンドを持つM(+) として最もよく記述され,M(iPr(2) -dad) ((3) =M(+) iPr(2) -dad (-).
- この電子構成であるM(+) iPr(2) -dad (-) は,これらの偽オクターエドルのニオビウムとタンタール複合体における観測された二磁性性を説明する.
- この発見は,低価変異金属複合体の従来型の電子構造モデルに異議を唱えている.
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