Ruthenium Pincer Complexes: Synthesis and Catalytic Applications

Abstract

Pincer‐based catalysts possess an exceptional balance of stability versus reactivity, aspects of fundamental interest in catalyst design. This balance has been well‐controlled by systematic ligand modifications along with the variation of the metal center. Ruthenium pincer complexes (RPCs), exhibit a versatile chemistry, serve as excellent precursors and find potential applications in many organic transformations. A large number of novel and valuable reactions has been developed using both stoichiometric and catalytic amounts of RPCs. Compared to the traditional ruthenium catalysts, pincer complexes often present high efficiency, selectivity and functional group tolerance. This review highlights different methodologies for the synthesis of RPCs and their catalytic applications for different reactions reported in the last decade. Additionally, the factors affecting the catalytic reactivity of the RPCs and the reaction mechanisms are discussed.magnified image

Unexpected Direct Hydride Transfer Mechanism for the Hydrogenation of Ethyl Acetate to Ethanol Catalyzed by SNS Pincer Ruthenium Complexes

“…Further improvement of current catalysts and the design of new, cost‐effective, metal complexes for catalytic hydrogenation of esters rely on a deep understanding of related reaction mechanisms . However, we are still lacking mechanistic insights into catalytic ester hydrogenation reactions . As early as 2006, Milstein and co‐workers proposed a plausible mechanism for the hydrogenation of nonactivated aromatic and aliphatic esters into alcohols catalyzed by a PNN pincer ruthenium hydride complex .…”

Metal–organic frameworks containing N-heterocyclic carbenes and their precursors

“…Thus, such ligands are applied in organometallic chemistry for the synthesis of highly active and very stable catalysts [132,133], which are much superior to phosphine-based catalysts. These NHC catalysts have shown good control over carbon-carbon, carbon-oxygen, and carbon-nitrogen bond formation or deletion, by their effectiveness for an array of rearrangement, addition, and group-transfer reactions [57,131,134].…”

Modern Organometallic Multidentate Ligand Design Strategies: The Birth of the Privileged “Pincer” Ligand Platform

“…The authors of this historical perspective further hope that this discussion has served as a useful introduction to the other manuscripts in this volume, all presented by the new leaders in the field of pincer chemistry. References [44][45][46][47][48][49][50][51][52][53][54][55][56] provide some relevant reviews that give excellent and detailed overviews of previous and current developments in the field of pincer chemistry and its applications. …”