Synthesis of NHC precursors. Commercially available 4,7-dibromo-2,1,3-benzothiadiazole (1) was chosen as a precursor for both phenyl and pentafluorophenyl substituted benzimidazolium salts 5 and 8 (Scheme 1). Suzuki coupling allowed for the installation of phenyl groups in the backbone motif, while subsequent reductive sulphur extrusion gave access to o-phenylenediamine derivative 2 in 72% yield over two steps. Next, the bicyclic benzimidazole skeleton was obtained using a standard cyclisation protocol with triethyl orthoformate, affording 3 in quantitative yield. Products 2 and 3 were obtained on a gram scale without purification by column chromatography. In the final step, the desired benzimidazolium salt 5 was obtained using copper-catalysed arylation with diphenyliodonium tetrafluoroborate. Worth highlighting is that such direct arylation of NH imidazole to imidazolium salt has never been reported in the literature. , This protocol gave a mixture of the desired N,N'-diphenylbenzimidazolium salt 5 (36% isolated yield) and neutral N-phenylbenzimidazole 4 (58% isolated yield) which were separated using column chromatography. The succeeding arylation of isolated 4 gave salt 5 in 77% yield, therefore the two subsequent arylation reactions lead to compound 5 in an 81% overall yield.