Pd(II)–N-heterocyclic carbene complexes of 2,6-bis{N-methyl-(imidazolium/benzimidazolium)}pyrazinechloride: Synthesis, structure, catalysis and theoretical studies

The multitopic pyrazine functionalized pro-ligand 2,6-bis(N-methylimidazolium)pyrazinedichloride, L-1; 2,6-bis(N-methylbenzimidazolium)pyrazinedichloride, L-2 and their respective Pd(II)–NHC complexes 1 and 2 have been synthesised and characterized by different spectroscopic methods and have been analyzed within a conceptual DFT framework. Single crystal X-ray structures of (L-1)PF6 and complex 1 have been determined. X-ray structure revels that 1 form a 12 member palladacycle. Both complex 1 and 2, catalyse the Suzuki coupling reaction very well and from experimental and theoretical findings it is concluded that complex 1 is slightly catalytically more active than 2.

Graphical abstractThe multitopic pyrazine functionalized CNC pincer proligands 2,6-bis(N-methyl-imidazolium/benzimidazium)pyrazinedichloride and their Pd(II) complexes have been synthesized and characterized by different spectroscopic methods and have been analyzed within a conceptual DFT framework. Pd(II)–N heterocyclic carbene complexes acts as good catalyst in C–C coupling reactions.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Multitopic pyrazine functionalized CNC pincer carbene ligands focused. ► Pyrazine functionalized N-heterocyclic carbene offer robust Pd(II)-complexes. ► Pd(II)–N heterocyclic carbene complexes are excellent catalyst in Suzuki coupling reaction.