Synthesis of unsymmetrical N-carboranyl NHCs: directing effect of the carborane anionElectronic supplementary information (ESI) available. CCDC 1028440 and 1028443. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4cc08267b

The syntheses of unsymmetrical N-heterocyclic carbenes (NHCs) that contain a single N-bound icosahedral carborane anion substituent are reported. Both anionic C-2 and doubly deprotonated dianionic C-2/C-5 NHC lithium complexes are isolated. The latter species is formed selectively, which reveals a surprising directing effect conveyed by icosahedral carborane anion substituents. The selective synthesis of unsymmetrically substituted anionic C-2 and dianionic C-2/C-5 N -carboranyl NHCs is reported, revealing a directing effect conveyed by the anionic carborane substituent.