Synthesis and Alkyne Insertion Reactions of NHC-Based Cyclometalated Ruthenium(II) Complexes

The series of NHC-based cyclometalated ruthenium­(II) complexes <b>2a</b>–<b>k</b> were synthesized by the reactions of aryl-substituted imidazolium salts with [(<i>p</i>-cymene)­RuCl₂]₂ under mild conditions. These complexes could react with alkynes in MeOH at 80 °C, through alkyne insertion and subsequent reductive elimination, to give the new kinds of imidazolium salts <b>3a</b>–<b>q</b> in high yields. All new compounds were fully characterized, and the molecular structures of <b>2a</b>–<b>d</b>,<b>f</b>,<b>g</b>,<b>i</b>–<b>k</b> were determined by single-crystal X-ray diffraction analysis