Synthesis and ROMP Chemistry of Decafluoroterphenoxide Molybdenum Imido Alkylidene and Ethylene Complexes

The bisDFTO alkylidene complexes of molybdenum Mo(NR)(CHCMe 2 Ph)(DFTO) 2 (R = 2,6-i-Pr 2 C 6 H 3, 2,6-Me 2 C 6 H 3, C 6 F 5, 1-adamantyl; DFTO = 2,6-(C 6 F 5 ) 2 C 6 H 3 O) and monoaryloxide monopyrrolide (MAP) complexes Mo(NR)(CHCMe 2 Ph)(Me 2 Pyr)(OAr) (Me 2 Pyr = 2,5-dimethylpyrrolide; R = C 6 F 5, OAr = DFTO, 2,6-dimesitylphenoxide (HMTO); R = 2,6-Me 2 C 6 H 3, OAr = DFTO) have been prepared in good yields. Addition of dicarbomethoxynorbornadiene (DCMNBD) to bisDFTO complexes yielded polymers that have a cis,isotactic structure. Polymerization of DCMNBD by Mo(NC 6 F 5 )(CHCMe 2 Ph)(Me 2 Pyr)(HMTO) gives a polymer that contains the expected cis,syndiotactic structure, but polymerization of DCMNBD by Mo(NR)(CHCMe 2 Ph)(Me 2 Pyr)(DFTO) (R = C 6 F 5, 2,6-Me 2 C 6 H 3 ) generates a polymer that has a cis,isotactic structure, the first observation of a cis,isotactic polymer prepared employing a MAP initiator. Norbornene is polymerized to give what is proposed to be highly tactic cis -polyNBE. Addition of ethylene to Mo(NC 6 F 5 )(CHCMe 2 Ph)(DFTO) 2 leads to formation of Mo(NC 6 F 5 )(CH 2 CH 2 )(DFTO) 2, which also behaves as an initiator for polymerization of DCMNBD to cis,isotactic -polyDCMNBD and norbornene to cis highly tactic polyNBE. Mo(NC 6 F 5 )(CH 2 CH 2 )(DFTO) 2 reacts with 3-methyl-3-phenylcyclopropene (MPCP) to give Mo(NC 6 F 5 )(CHCHCMePh)(DFTO) 2 in ∼50% yield.