N-Heterocyclic olefin stabilized boron dication

Abstract

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.