Low-Melting Dialkyl- and Bis(polyfluoroalkyl)-Substituted 1,1‘-Methylenebis(imidazolium) and 1,1‘-Methylenebis(1,2,4-triazolium) Bis(trifluoromethanesulfonyl)amides: Ionic Liquids Leading to Bis(N-heterocyclic carbene) Complexes of Palladium

Ionic liquids with pincer dicationic nuclei, 2a−6a and 2b−6b, were prepared from either
1,1‘-methylenebis(imidazole) or 1,1‘-methylenebis(1,2,4-triazole) via quaternization with alkyl
or polyfluoroalkyl halides under classical or microwave irradiation conditions. Palladium-catalyzed Heck cross-coupling reactions were performed successfully in the ionic liquid 3a.
A single-crystal X-ray structure of a bis(N-heterocyclic carbene) complex of palladium (7)
formed in the ionic liquid catalyst system supports its likelihood as the active catalyst.