Synthesis and characterization of non-chelating ruthenium–indenylidene olefin metathesis catalysts derived from substituted 1,1-diphenyl-2-propyn-1-ols
We report on the synthesis and characterization of the first generation of modified non-chelating indenylidene ruthenium catalysts denoted as RuCl2(4-methyl-3-(o-tolyl)-1-indenylidene)(PCy3)25a, RuCl2(3-(p-fluorophenyl)-1-indenylidene)(PCy3)25b, RuCl2(3-(2,6-xylyl)-1-indenylidene)(PCy3)25c and RuCl2(3-(1-naphthyl)-1-indenylidene)(PCy3)25d. The obtained complexes of 5a–d were characterized by means of NMR spectroscopy and elemental analysis. Moreover the structures of 5a–d were confirmed by single-crystal X-ray diffraction and compared with the standard ruthenium indenylidene complex 3 and the chelating benzylidene complex 2. Additionally, the catalytic performances of the obtained complexes 5a–d were evaluated in various metathesis reactions demonstrating that the ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) reactions revealed a similar catalytic activity in comparison with the reference indenylidene catalyst 3.