断捨離 する の に 耐え難い: ボロン クラスタ の 芳香 性 は 根本 的 な 構造 変化 に 耐え ます
Jordi Poater1,2, Clara Viñas3, Ines Bennour3
1Departament de Quı́mica Inorgànica i Orgànica & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.
Journal of the American Chemical Society
|April 24, 2020
まとめ
メタ-C2B10H12のようなカルボランの安定性は,アロマティック度ではなく,炭素原子の配置に関連しています. ボロンのクラスターの芳香性は,ニド・カルボランでも構造変化によって持続する.
科学分野:
- 無機化学
- コンピュータ化学
- 材料科学
背景:
- カーボラン (C2B10H12) は同位体であり,メタカーボラン (m-C2B10H12) はオルトカーボラン (o-C2B10H12) よりも安定している.
- クロソボランとカルボランは,その芳香特性で知られており,その特徴はしばしばその安定性に関連している.
- 伝統的な見解では,サンドイッチメタルロセンはサンドイッチメタルラビス (((dicarbollides)) と等しく,同様の電子および構造的性質を示唆しています.
研究 の 目的:
- 炭酸ガスの同位体におけるデボロン化難度,熱力学的安定性,および芳香性との関係を調査する.
- ニドカルボランを含むボロンクラスターの芳香性の持続性を調査し,伝統的な芳香系と比較する.
- サンドイッチメタロセンとメタルラビス (二酸化炭素) の芳香性特性を区別する.
主な方法:
- o-C2B10H12を加熱してm-C2B10H12へのイソメリゼーションとデボロン化を誘導する実験研究.
- 熱力学的な安定性と電子構造を分析するための密度関数理論 (DFT) の計算.
- 核磁共振 (NMR) スペクトロスコーピー (1Hと11B) で,電子電流とニドカルボランの芳香性を探知する.
主要な成果:
- m-C2B10H12の熱力学的安定性の向上は,芳香性の違いではなく,炭素原子の特殊な配置に起因する.
- アロマティック性はニドカルボランに存在することが示され,ボロンクラスター内の重要な構造変化に対する耐性を示しています.
- メタルラビス (dicarbollides) は,サンドイッチメタロセンのリガンドで観察された局所的芳香と対照的に,全体的な芳香性を示す.
- NMRスペクトロスコーピーを用いた[C2B9H12]-における二酸化流の実験的証拠は,これらのクラスターにおける芳香性を確認している.
結論:
- ボロンクラスターの芳香性は,クローソからニードーフレームワークへの移行を含む実質的な構造変化を生き残る堅固な特徴です.
- カーボランの安定性は,単に芳香度によってではなく,主に原子位置によって支配される.
- メタルラビス (ディカルボリド) とメタルロセンの間には,芳香度 (グローバルとローカル) の明確な区別がある.
- クラスタの電子要求パラダイムが支持され,クローソとニドの両方の種の芳香性の性質が説明されます.
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