Olefin Metathesis Reactions Initiated by d2 Molybdenum or Tungsten Complexes

Dimeric or monomeric imido complexes of Mo(IV) or W(IV) will slowly catalyze some olefin metathesis reactions, although it is estimated that <2% of the d 2 species is “activated” by the olefin. An ethylene adduct of {W(NAr‘)[OCMe 2 (CF 3 )] 2 } 2 can be isolated, which upon heating is transformed into a new dimeric species that contains an ethyl group and a CH activated ortho methyl group in the NAr‘ ligand.