Evaluation of ionic liquid soluble imidazolium tetrachloropalladate pre-catalysts in Suzuki coupling reactions

Imidazolium salts with aromatic groups 1,3-bis(9-anthracenylmethyl)imidazolium chloride ([Bamim]Cl), 1,3-bis(1-naphthalenylmethyl)imidazolium chloride ([Bnmim]Cl) and 1,3-bis(benzylmethyl)imidazolium chloride ([Bbmim]Cl) were reacted with PdCl2 forming the analogous tetrachloropalladate salts. These palladium-containing salts were evaluated as pre-catalysts in Suzuki cross-coupling reactions in ionic liquids generally resulting in high conversions. The formation of palladium nanoparticles is observed and their role in the overall catalytic mechanism is discussed.

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► Three imidazolium tetrachloropalladates were synthesized and crystal structures identified.
► They proved to be active pre-catalyst for Suzuki reactions.
► The effect of cations on the efficiency of the reaction were studied and rationalized.