Tridentate, anionic tethered N-heterocyclic carbene of Pd(II) complexes

The synthesis of a series of azolium salts such as azolium iodides and chlorides having both N-anionic functional group and N-alkyl group have been developed. Reaction of azolium iodides or chlorides with Ag2O gave the corresponding NHC–Ag complexes. It was found that the resulting NHC–Ag complexes derived from azolium iodides or chlorides differ in their physical properties. The azolium chlorides as well as azolium iodides were successfully converted into the NHC–Ag complexes, which subsequently reacted with PdCl2(CH3CN)2 to give the anionic amidate/NHC–Pd complexes. Thus, a variety of the NHC–Pd complexes could be obtained from benzimidazolium and imidazolium salts.