扩散核磁共振测量催化条件下的阴性黄金 (I) 复合物:对比和溶剂效应
Filippo Campagnolo1, Eleonora Aneggi1, Walter Baratta1
1Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy.
Molecules (Basel, Switzerland)
|July 13, 2024
概括
这项研究量化了黄金中离子物种的催化氧化,揭示了对催化活性的反和溶剂效应. 较低的离子解离 (α) 与较高的活性相关,特别是在极绿色溶剂中.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 解决方案化学 解决方案化学
背景情况:
- 含有N-异环碳素 (NHC) 的黄金 (I) 复合物是氧化的有效催化剂.
- 了解离子和离子对的物种化对于优化催化性能至关重要.
- 以前的研究表明,催化活性和离子对解离之间存在联系,但实验证据有限.
研究的目的:
- 通过实验确定黄金中自由离子,离子对和聚合物的度.
- 为了研究反离子性质和溶剂介电常数对离子物种化和催化活性的影响.
- 要将离子解离度 (α) 与催化效率 (转换频率,TOF) 相对应.
主要方法:
- 在催化条件下使用扩散顺序光谱法 (DOSY) NMR (H和F).
- 用各种溶剂进行测量,包括和具有高介电常数的绿色溶剂.
- 离子对/自由离子平衡的解离度 (α) 是根据NMR数据计算的.
主要成果:
- 对比标识显著影响甲中的α:OTs-和OTf-产生低α (高离子配对),而BF-和BARF显示更高α (更多的自由离子).
- 催化活性通常随着较低的α增加,这归因于离子在激活甲醇中的作用.
- 在极绿色溶剂中,观察到高α值,表明涉及极性功能的溶剂特定激活机制.
结论:
- 实验 DOSY NMR 数据证实,较低离子对解离 (较低α) 增强了金催化氧化活性.
- 选择对电离子和溶剂极性是影响催化性能的关键因素.
- 绿色溶剂中的极性功能在甲醇激活中起着关键作用,补充了反的作用.
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