Boron mono- and di-cations featuring a nucleophilic N-heterocyclic olefin and the pentamethylcyclopentadienyl substituent have been prepared and structurally characterized. Experimental and theoretical investigations show that [η5-Cp*B-NHO]2+is considerably more Lewis acidic than [η5-Cp*B-IMes]2+due to the steric congestion imposed by the bent geometry of NHO around the central boron atom.
Boron