On the road to isolable geminal carbodications

Recent advances in the isolation of masked gem-carbodications have shown that such species may be more accessible than we thought. This perspective article summarizes the milestones of the last 140 years of research and aims to point the way toward the isolation of species containing true four-valence-electron carbon. Currently, strong mesomeric donation or coordination by donor ligands is used to stabilize such dications. Achieving true localization of both charges on a single atom will require smart combinations of inductive donation, hyperconjugation, and steric hindrance.