Oxidative addition of imidazolium salts to Ni⁰ and Pd ⁰: Synthesis and structural characterization of unusually stable metal-hydride complexes

C-H activation of imidazolium salts by coordinatively unsaturated low-valent Ni and Pd complexes occurs under mild conditions. Surprisingly stable hydridometal-N-heterocyclic carbene complexes were isolated (see scheme), which demonstrates the ease with which imidazolium-based ionic liquids may react with transition-metal complexes during catalysis.