Synthesis of pentafluorophenyl substituted derivative 8 turned out to be a more synthetic challenge (see Supporting Information for experimental details on pre-ligands synthesis). A Kumada-Corriu coupling was successfully employed to graft pentafluorophenyl groups into the benzothiadiazole motif. The subsequent reductive sulphur extrusion step gave o-phenylenediamine derivative 6 in 55% yield over the two steps. Unlike the synthesis of salt 5, the N-phenyl groups were first installed through a Buchwald-Hartwig amination, giving compound 7 in 21% isolated yield.