Reactivity of carbene•phosphine dimers: proton affinity revisited

Abstract

The gas phase reactivity of N ‐heterocyclic carbenes versus tricyclohexylphosphine (PCy 3 ) is examined computationally and experimentally. New measurements indicate that dimethylimidazol‐ and 1‐ethyl‐3‐methylimidazol‐2‐ylidene are more basic than PCy 3 , in contrast to previous measurements made by us and by others. Proton‐bound dimers of the carbenes and PCy 3 are also found to exhibit interesting reactivity involving phosphine alkylation, cyclohexene elimination, and/or ethylene elimination. This novel reactivity is further probed and discussed. Copyright © 2011 John Wiley & Sons, Ltd.