Ruthenium–Olefin Complexes: Effect of Ligand Variation upon Geometry

The development of a model system to study ruthenium–olefin complexes relevant to the mechanism of olefin metathesis has been reported recently. Upon addition of the ligand precursor 1,2‐divinylbenzene to [RuCl 2 (Py) 2 (H 2 IMes)(CHPh)] (H 2 IMes=1,3‐dimesityl‐4,5‐dihydroimidazol‐2‐ylidene), two ruthenium–olefin adducts are formed. Based on 1 H NMR spectroscopy experiments and X‐ray crystallographic analysis, these complexes are assigned as side‐bound isomers in which the olefin and H 2 IMes ligands are coordinated cis to each other. Herein is reported an investigation of the generality of these observations through variation of the N ‐heterocyclic carbene ligand and the ligand precursor.