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[HC[CH(SiMe(3)) ((SnMe(3)))))))) 的隔离和结构:一个非常稳定的sec-alkyl离子
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
概括
研究人员合成了新型含锡的sec-alkyl carbocation盐,在没有超酸的情况下表现出了显著的热稳定性. 这些稳定的碳酸有效地启动了聚合反应.
科学领域:
- 有机金属化学 有机金属化学
- 碳化物化学 碳化物化学
- 聚合物科学 聚合物科学
背景情况:
- 传统的carbocations通常需要极端条件 (超酸,弱协调阳离子) 进行隔离和稳定.
- 锡替代有机化合物具有独特的电子特性,可以影响化学反应性和稳定性.
研究的目的:
- 为了合成和表征新的,可分离的sec-alkyl carbocation盐.
- 调查锡替代剂对碳酸稳定性的稳定作用.
- 评估这些新型碳酸作为聚合物的启动剂的潜力.
主要方法:
- 在化的存在下,替代的与金属化物 (MCl4) 的反应.
- 由此产生的碳酸盐的分离和表征.
- 进行X射线晶体学和密度函数理论 (DFT) 计算以阐明结构和稳定性.
- 使用异布丁,异烯和α-甲基烯的聚合实验.
主要成果:
- 热稳定的sec-alkyl carbocation盐的第一个分离,[HC{CH(R) SnMe3}2]+M2Cl9- (M = Zr, Hf).
- 在没有超酸性介质或弱协调性离子的情况下证明了稳定性.
- DFT计算和晶体结构分析揭示了Sn替代物极化和过度结合作为关键的稳定因素.
- 锡表现出明显强大的稳定作用比.
- 碳酸被证明是异布丁,异烯和α-甲基烯聚合的有效发起者.
结论:
- 锡替代剂给sec-alkyl carbocations赋予了显著和意想不到的稳定性.
- 这些新型的有机蛋白碳酸代表了一类新的稳定基离子物种.
- 它们作为聚合化启动剂的有效性为新的聚合物合成策略开辟了道路.
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