Fusing 10-vertex closo-carborane anions with N-heterocyclic carbenes

Discovered by Knoth in 1964, the 10-vertex closo-carborane anion [HCB9H91-] is a classical bicapped square antiprism that contains an unusual pentacoordinate carbon center. Compared to its larger icosahedral cousin [HCB11H111-], few investigations have been made into its use as a weakly coordinating anion or as a ligand substituent. Here we show that it is possible to prepare both a dianionic N-heterocyclic carbene (NHC) Li+ adduct as well as a trianionic C-2, C-5 dilithio species featuring two 10-vertex carborane anion substituents. All compounds were characterized via multinuclear NMR spectroscopy, single crystal X-ray diffraction, and HRMS when possible.

Automated summary

In this study, the synthesis of two 10-vertex carborane anion substituents was achieved, demonstrating the feasibility of preparing dianionic N-heterocyclic carbene (NHC) Li+ adduct.