Diversification of the Carbodicarbene Class by Embedding an Anionic Component in its Scaffold

Carbodicarbene (CDC) has become an emerging ligand in many fields due to its strong σ-donating ability. <We report the first synthesis of the anionic CDC Pd complexes containing a BF₂^- moiety within the framework to leverage the electronic feature of carbon carbone. The elucidation of X-ray crystal structures, ligand competition as well as transmetallation experiments suggest that the anionic moiety has enhanced the overall donor strength of the traditional neutral CDC. Importantly, this anionic scaffold exhibits a facile second coordination toward Au(I), Ag(I) and Pd(II) without any external ligand assistance, whereas previously reported neutral pincer CDC complexes do not possess a two-fold donor capacity. The analysis of the bonding situation via theoretical methods shows that the description of the anionic CDC moieties in terms of dative bonding is preferred over the model of delocalized positive charge, as it accounts for the two-fold donor ability of the divalent carbon atom, preserving a characteristic feature of a carbone.