Magnesium Complexes with Isomeric Pyrazol‐4‐ylidene and Imidazol‐2‐ylidene Ligands

Dimagnesium(I) complexes [{(Arnacnac)Mg}2], where Arnacnac = HC(MeCNAr)2, Ar Dip 2,6-iPr2-C6H3, Dep 2,6-Et2-C6H3, Mes 2,4,6-Me3-C6H2, react with iodoarenes in oxidative addition reactions. With iodobenzene, magnesium phenyl and iodide complex fragments were obtained, from a reaction 4-iodo-1,2,3,5-tetramethylpyrazolium iodide, [MePZI]I, the pyrazol-4-ylidene [(Dipnacnac)MgI(MePZ)] was structurally characterised, alongside other products. The isomeric imidazol-2-ylidene [(Dipnacnac)MgI(MeNHC)], MeNHC is 1,3,4,5-tetramethylimidazol-2-ylidene, prepared characterised. X-ray crystal structure determinations DFT computational studies have been carried out to compare related complexes. results show that MePZ ligand higher energy more nucleophilic than its common carbene.