Fusing Dicarbollide Ions with N‐Heterocyclic Carbenes. Issue 33 (17th July 2017)

• Record Type: Journal Article
• Authors: Estrada, Jess; Lavallo, Vincent
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 33(2017)
• Page Start: 9906
• Page End: 9909
• Publication Date: 2017-07-17
• Subjects: carbenoids -- carborane anions -- catalysis -- dicarbollides -- N-heterocyclic carbenes; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201705857
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: 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. Abstract : A happy marriage : Over 50 years after Hawthorne's seminal discovery of the dicarbollide ion, it is demonstrated that this classical cyclopentadienyl anion mimic can be directly fused to stable carbenes. The marriage of these two unusual classes of carbon‐containing molecules introduces a new concept in NHC ligand design.