Access to cationic polyhedral carboranes via dynamic cage surgery with N-heterocyclic carbenes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34404809.
- Also identified by DOI 10.1038/s41467-021-25277-0 and PMC identifier 8371172.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Polyhedral boranes and heteroboranes appear almost exclusively as neutral or anionic species, while the cationic ones are protonated at exoskeletal heteroatoms or they are instable. Here we report the reactivity of 10-vertex closo-dicarbadecaboranes with one or two equivalents of N-heterocyclic carbene to 10-vertex nido mono- and/or bis-carbene adducts, respectively. These complexes easily undergo a reaction with HCl to give cages of stable and water soluble 10-vertex nido-type cations with protonation in the form of a BHB bridge or 10-vertex closo-type cations containing one carbene ligand when originating from closo-1,10-dicarbadecaborane. The reaction of a 10-vertex nido mono-carbene adduct with phosphorus trichloride gives nido-11-vertex 2-phospha-7,8-dicarbaundecaborane, which undergoes an oxidation of the phosphorus atom to P = O, while the product of a bis-carbene adduct reaction is best described as a distorted C<sub>2</sub>B<sub>6</sub>H<sub>8</sub> fragment bridged by the (BH)<sub>2</sub>PCl<sub>2</sub><sup>+</sup> moiety.