An efficient route to unsymmetrical bis(azolium) salts: CCC-NHC pincer ligand complex precursors

The coupling of N-heterocyclic azoles (imidazoles, benzimidazoles, triazoles) to bromobenzenes (1,2-; 1,3-; or 1,4) in a step-wise, sequential manner was accomplished by manipulation of reaction time and stoichiometry, which provided straight-forward access to unsymmetrical bis(azolium) salts in only three isolation steps from commercially-available starting materials. Eight mono(azole) substituted bromobenzenes, four mono(azolium)bromobenzene salts, twelve unsymmetrical bis(azole)benzenes, and fourteen unsymmetrical bis(azolium) salts, which are precursors for pincer ligand complexes, are reported.

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