Fusing Dicarbollide Ions with N‐Heterocyclic Carbenes

Discovered by Hawthorne in 1965, dicarbollide ions are an intriguing class of nido‐carboranes that mimic the behavior of the cyclopentadienyl anion. Herein, we show that it is possible to directly link the dicarbollide ion to an N‐heterocyclic carbene (NHC) to form an isolable N‐dicarbollide‐substituted NHC dianion. This molecule can be accessed by the sequential double deprotonation of a mono‐nido‐carboranyl imidazolium zwitterion. As revealed by a single‐crystal X‐ray diffraction study, the first deprotonation leads to a monoanionic dicarbollide ion that adopts a bis(dicarbollide) structure in the solid state. Subsequent deprotonation of this monoanion leads to the first N‐dicarbollide NHC, which was fully characterized by multinuclear NMR spectroscopy as well as single‐crystal X‐ray diffraction.