title: Proton affinities of N-heterocyclic carbene super bases.
abstract: The gas-phase proton affinity of the N-heterocyclic carbene, 1-ethyl-3-methylimidazol-2-ylidene, was determined to be 251.3 +/- 4 kcal/mol using the kinetic method, a value which makes the carbene one of the strongest bases reported thus far. Density functional theory calculations have been carried out at the B3LYP/6-31+G(d) level to compare the high experimental value with that estimated theoretically. Experimental results also show that two other N-heterocyclic carbenes with larger substituents have even higher proton affinities. [structure: see text]
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Dina R
authors.initials: DR
authors.lastname: Justes
authors.forename: R Graham
authors.initials: RG
authors.lastname: Cooks