Synthesis of bis-N-alkyl imidazolium salts and their palladium(0)(NHC)(η2-MA)2 complexes

New N-Alkyl-substituted imidazolium salts as well as a series of their corresponding [Pd(NHC)(MA)2] complexes have been obtained by three routes in good yield. The previously reported synthesis for the analogous N-aryl substituted [Pd(NHC)(MA)2] complexes has been improved. The N-alkyl-substituted [Pd(NHC)(MA)2] complexes are thermally more labile than their N-aryl counterparts. Catalytic transfer semi-hydrogenation of phenylpropyne resulted in good to excellent chemo- and stereo- selectivity conversion into (Z)-phenylpropene. The size of the alkyl substituents correlates with the rate of hydrogenation in the sense that more bulky substituents give rise to faster transfer hydrogenation rates. Copyright © 2012 John Wiley & Sons, Ltd.