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[HC[CH(SiMe(3)) ((SnMe(3)) ]](2)](+) の分離と構造:非常に安定したセックアルキルカチオンである
Mark Schormann1, Shaun Garratt, David L Hughes
1Wolfson Materials and Catalysis Centre, School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
Journal of the American Chemical Society
|September 19, 2002
まとめ
研究者らは,新しい亜鉛を含むセックアルキルカルボケーション塩を合成し,超酸性物質なしで顕著な熱安定性を示しました. これらの安定したカルボケーションは,ポリメリゼーション反応を効果的に開始します.
科学分野:
- 有機金属化学 有機金属化学
- カーボケーション化学 カーボケーション化学
- ポリマーサイエンスの科学
背景:
- 伝統的なカルボケーションは,孤立と安定のために,しばしば極端な条件 (超酸性,弱調整アニオン) を要求する.
- 亜鉛置換有機化合物は,化学反応性と安定性に影響するユニークな電子特性を有しています.
研究 の 目的:
- 新しい,分離可能なセックアルキルカルボケーション塩を合成し,特徴づけます.
- カルボケーションの安定性に対するチンの置換剤の安定効果を調査する.
- ポリメリゼーションのイニシアターとしてのこれらの新しいカルボケーションの可能性を評価する.
主な方法:
- チン置換プロペンの金属ハロイド (MCl4) とチン塩化物の存在における反応.
- 結果となるカルボケーション塩の分離と特徴付け.
- 構造と安定性を明らかにするために,X線結晶学と密度関数理論 (DFT) の計算を行いました.
- イソブテン,イソプレン,アルファメチルスタイレンを用いたポリメリゼーション実験.
主要な成果:
- 熱的に安定したセックアルキルカルボケーション塩, [HC{CH(R) SnMe3}2]+M2Cl9- (M = Zr, Hf) の最初の分離.
- 超酸性介質や弱調整アニオンなしで安定性が実証されています.
- DFTの計算と結晶構造の分析により,Sn置換物分極化とハイパー結合が主要な安定化因子であることが明らかになった.
- スチンは,シリコンよりも著しく強い安定効果を示した.
- カーボカチオンは,イソブテン,イソプレン,アルファメチルstyreneのポリメリゼーションのための効果的なイニシアターであることが証明されました.
結論:
- スチンの置換剤は,セックアルキルカルボカシオンに有意かつ予期せぬ安定性を与えます.
- これらの新種のオルガノチンカルボケーションは,安定したカチオン性種の新種を代表しています.
- ポリメリゼーションのイニシアターとしてのそれらの有効性は,新しいポリマー合成戦略の道を開く.
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