engleski

Solid-state synthesis and catalytic potential of dicyclopalladated azobenzenes

Selective activation of unreactive C-H bonds using a ligand-directed approach is one of the most popular synthetic protocols for obtaining organometallic compounds. Palladium cyclometallated compounds or palladacycles are common catalysts in cross-coupling reactions and proposed intermediates in metal-catalyzed C-H bond functionalization. In recent years, the strong effect of acidic additives on the pre-activation step of trimeric palladium acetate, [Pd(OAc)2]3, in C-H bond activation and functionalization was reported. While the synthesis of palladacycles and the mechanism of these reactions are well established in solution, the solid-state approach is still being investigated. In contrast to the reactions carried out in the solution, which are often time-consuming and performed in harmful solvents, the mechanochemical protocols can significantly shorten the reaction times and lead to the almost total omission of solvents. In this work, we present a simple, fast, and environmentally-friendly mechanochemical procedure for the synthesis of a series of dimeric dicyclopalladated azobenzenes promoted by selected organic acids. Reaction monitoring using in situ Raman spectroscopy enabled insight into the reaction dynamics while NMR and IR spectroscopy were used for characterization of dicyclopalladated products. Solid-state Suzuki- Miyaura reaction of 4-bromoazobenzene and phenylboronic acid was used as a model reaction for testing the catalytic potential of the obtained palladacycles.

Palladacycles ; Catalysis ; Solid-state ; Mechanochemistry ; C-H bond activation

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