Samudrala Kavyasripriya K, Conley Matthew P
Department of Chemistry, University of California, Riverside, California 92521, USA.
Chem Commun (Camb). 2023 Apr 4;59(28):4115-4127. doi: 10.1039/d3cc00047h.
Well-defined organometallics supported on high surface area oxides are promising heterogeneous catalysts. An important design factor in these materials is how the metal interacts with the functionalities on an oxide support, commonly anionic X-type ligands derived from the reaction of an organometallic M-R with an -OH site on the oxide. The metal can either form a covalent M-O bond or form an electrostatic M⋯O ion-pair, which impacts how well-defined organometallics will interact with substrates in catalytic reactions. A less common reaction pathway involves the reaction of a Lewis site on the oxide with the organometallic, resulting in abstraction to form an ion-pair, which is relevant to industrial olefin polymerization catalysts. This Feature Article views the spectrum of reactivity between an organometallic and an oxide through the prism of Brønsted and/or Lewis acidity of surface sites and draws analogies to the molecular frame where Lewis and Brønsted acids are known to form reactive ion-pairs. Applications of the well-defined sites developed in this article are also discussed.
负载在高比表面积氧化物上的结构明确的有机金属化合物是很有前景的多相催化剂。这些材料的一个重要设计因素是金属如何与氧化物载体上的官能团相互作用，这些官能团通常是由有机金属化合物M-R与氧化物上的-OH位点反应衍生出的阴离子X型配体。金属既可以形成共价M-O键，也可以形成静电M⋯O离子对，这会影响结构明确的有机金属化合物在催化反应中与底物的相互作用程度。一种不太常见的反应途径涉及氧化物上的路易斯位点与有机金属化合物的反应，导致形成离子对，这与工业烯烃聚合催化剂相关。这篇专题文章通过表面位点的布朗斯特和/或路易斯酸度的视角来审视有机金属化合物与氧化物之间的反应谱，并与已知路易斯酸和布朗斯特酸会形成反应性离子对的分子框架进行类比。本文还讨论了所开发的结构明确位点的应用。
