Mechanochemical synthesis of corannulene flanked N-heterocyclic carbene (NHC) precursors and preparation of their metal complexes

The synthesis of new compounds is an important pillar of organic chemistry with implications in adjacent fields. In this regard, over the last decades huge efforts have been made not only to produce new molecular entities but also to develop more efficient sustainable synthetic methodologies due to the increasing concerns over environmental sustainability. In this context, we have developed synthetic routes to novel corannulene-flanked imidazolium bromide NHC precursors both in the solid state and solution phases. Our work presents a comprehensive comparative study of mechanochemical routes and conventional solution-based methods. The green metrics comparison performed for both routes reveals ball-milling generation of these compounds to be an environmentally greener technique to produce such precursors compared to conventional solvent-based methods. In addition, we have demonstrated proof-of-concept of the herein reported corannulene flanked NHCs to be robust ligands to transition metals and their ligand substitution reactions.