聚或复合物的与1-乙烯类同类物的互转
Sumeng Liu1, Maxime Boudjelel1, Richard R Schrock1
1Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States.
这项研究表明,和复合物在特定酸催化时相互转化为 styrene 和 1-phenethylidene 形式. 反应机制涉及质子化和脱质子化步骤,其中偏好的是酸中间体中的α-脱质子化.
科学领域:
- 有机金属化学
- 催化剂
- 反应机制
背景情况:
- 和复合物与庞大的胺和乙烯配体在催化过程中至关重要.
- 了解烯和烯复合物的反应性是设计新催化过程的关键.
- styrene 和 1-phenethylidene 复合体之间的相互转换为研究联体动态提供了一个模型.
研究的目的:
- 研究 (II) styrene 和1-phenethylidene 复合物的酸催化相互转化.
- 阐明反应机制,包括关键中间体和速率决定的步骤.
- 在类似条件下比较和类型的反应性.
主要方法:
- 在45°C的C6和D6中使用HNM光谱的平衡研究.
- 通过使用强的布伦斯特德酸生成拟议的1-乙烯介质,如[[Et2O) 2H][B(C6F5) 4.
- 动力分析以确定速率常数和识别缓慢的步骤.
- 通过X射线结晶学来确定介质的结构.
主要成果:
- 形成了Mo () () () () () 和Mo () () () () 的平衡混合物,其K (eq) = 0.36.
- 相互转换通过1 - 乙烯介质进行,优先进行α - 脱 (比率为~10:1比β - 脱).
- 聚烯复合物的质子化是缓慢的步骤 (k1 = 0.158(4) L/(mol·min);其他质子源是无效的催化剂.
- 类似物W (NAr) (CMePh) (OSiPh) (3) (2) 也经过K (eq) = 0.47的相互转换.
结论:
- styrene 和 1-phenethylidene 复合物的酸催化相互转化是一个可逆的过程.
- 该机制涉及不同的质子化和脱质子化步骤,其中包括中间的区域选择性脱质子化.
- 观察到的反应性突出显示了金属中心和配体环境对催化路径的影响.
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