Exploring the reactivity of 1,3-dimethyl-2-methyleneimidazoline, an highly polarized N-heterocyclic olefin (NHO), toward Ni(II).

Our previous studies on the synthesis and reactivity of 1,3-dialkylimidazolium-2-carboxylates and related 1,3-dialkylimidazol-2-ylidenes evidenced an unexpected “double methylation” of the 2-ylidene intermediate with dimethylcarbonate at high temperature affording 1,3-dimethyl-2-ethylimidazolium compounds. 2-alkyl substituted imidazolium compounds have found application as electrolytes for electrochemical devices and as “tasks specific ionic liquids” in the reduction of CO2 to formic acid. Concerning the 2-methyl-substituted imidazolium cation (i.e. 1,2,3-trimethylimidazolium cation), it has been reported that it may undergo proton abstraction by strong bases (as NaH) affording a 1,3-dimethyl-2-methyleneimidazoline, an highly polarized N-heterocyclic olefin (NHO) with a strongly polarized exocyclic C-C bond. We report results about the coordination of the 1,3-dimethyl- 2-methyleneimidazoline ligand to Ni(II) complexes.