Non-symmetrical, potentially redox non-innocent imino NHC pyridine 'pincers' via a zinc ion template-assisted synthesis.

New non-symmetrical, redox-active imino NHC pyridine pincer ligands, 2-(R-imidazol-2-ylidene)-6-(RN[double bond, length as m-dash]CH)-pyridine (R = 2,6-diisopropylphenyl (DiPP), R = 2,4,6-trimethylphenyl (Mes), 4B; R = R = DiPP, 4C), have been accessed by a Zn-promoted modular synthesis involving the quaternization of R-imidazole by [Zn(κNκN)(2-(RN[double bond, length as m-dash]CH)-6-bromo-pyridine)Cl], followed by Zn removal and deprotonation of imidazolium pro-ligands. Redox active forms of 4B were implicated in the two complexes obtained by its reaction with FeBr/KC; metrical data analysis pointed to the occurrence of radical anionic and dianionic redox states of 4B.