Syntheses and catalytic activities of homogenous and hierarchical ZSM-5 grafted Pd(II) dicarbene complex of imidazole based ionic liquids

Pd(II) dicarbene complex of imidazole based cyclic and acyclic ionic liquids were prepared and their catalytic activities were compared in the Heck and the Sonogashira reactions of deactivated and economical bromobenzene/chlorobenzene. Acyclic Pd complex was found to be more active than the cyclic one. Geometrically optimized structures of cyclic and acyclic Pd complexes, which was computed using density functional method was able to explain the low activity of cyclic Pd complex. Further, these catalysts were grafted on hierarchical ZSM-5 surface and their catalytic activity and recyclability were investigated. Pd(II) dicarbene complex grafted on hierarchical ZSM-5 were found to be efficient and recyclable catalysts for CC coupling reactions. Catalysts were found to be stable and show negligible loss in activity even after the five cycles.

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► Pd(II) dicarbene complex of imidazole based ionic liquids were prepared.
► Pd(II) dicarbene complex was grafted on hierarchical ZSM-5.
► Catalysts were active for economical bromobenzene in CC coupling reactions.
► Hierarchical ZSM-5 grafted complex were reusable with no loss in activity.