Carbene–bridge–carbene ensembles: tunable diradicaloids for singlet fission?

Herein, we present anew class of singlet fission (SF) materials based on diradicaloids of carbene scaffolds,n amely cyclic (alkyl)(amino)carbenes (CAACs). Our modular approach allows the tuning of two key SF criteria:the steric factor and the diradical character.I nt urn, we modified the energy landscapes of excited states in as ystematic manner to accommodate the needs for SF.W er eport the first example of intermolecular SF in solution by dimer self-assembly at cryogenic temperatures.

Only sterics and aromaticity control whether radical olefin cations are stable.