10.1021/om300703p.s001 Xavier Bantreil Xavier Bantreil Albert Poater Albert Poater César A. Urbina-Blanco César A. Urbina-Blanco Yannick D. Bidal Yannick D. Bidal Laura Falivene Laura Falivene Rebecca A. M. Randall Rebecca A. M. Randall Luigi Cavallo Luigi Cavallo Alexandra M. Z. Slawin Alexandra M. Z. Slawin Catherine S. J. Cazin Catherine S. J. Cazin Synthesis and Reactivity of Ruthenium Phosphite Indenylidene Complexes American Chemical Society 2012 metathesi catalyst loadings Ruthenium Phosphite Indenylidene ComplexesThe synthesis precatalyst NHC ligands cis complexes cis configuration NMR experiments trans counterparts phosphite 2012-11-12 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Synthesis_and_Reactivity_of_Ruthenium_Phosphite_Indenylidene_Complexes/2470288 The synthesis of the four olefin metathesis precatalysts <b>Caz-1a</b>–<b>d</b>, featuring the NHC ligand <i>N</i>,<i>N′</i>-bis­(2,4,6-trimethylphenyl)­imidazolin-2-ylidene (SIMes) and four different phosphites (P­(O<sup><i>i</i></sup>Pr)<sub>3</sub>, P­(OPh)<sub>3</sub>, P­(OEt)<sub>3</sub>, and P­(OMe)<sub>3</sub>), is reported. The complexes are readily synthesized from commercially available [RuCl<sub>2</sub>(3-phenylinden-1-ylidene)­(pyridine)­(SIMes)] (<b>Ind-III</b>) in yields of up to 88%. These complexes adopt an unusual cis configuration between the phosphite and the NHC ligands. NMR experiments and computational studies confirm that the cis complexes are thermodynamically favored in comparison to their trans counterparts. In addition, the isomerization from trans to cis occurs via a mononuclear and non-dissociative mechanism. Among the four precatalysts, <i>cis</i>-<b>Caz-1a</b>, featuring a P­(O<sup><i>i</i></sup>Pr)<sub>3</sub> ligand, displays the highest activity in ring-closing metathesis and cross-metathesis transformations. Experiments at low catalyst loadings demonstrated the potential of this catalyst, allowing better conversions than with commonly used commercially available precatalysts.