Stereospecific Ring-Opening Metathesis Polymerization (ROMP) of Norbornene and Tetracyclododecene by Mo and W Initiators

Abstract

We report the synthesis of >98% cis,isotactic and cis,syndiotactic polynorbornene (poly(NBE)) and poly(endo,anti-tetracyclododecene) (poly(TCD)). Cis,isotactic poly(NBE) and poly(TCD) were prepared employing Mo-based biphenolate imido alkylidene initiators, Mo(NR)(CHCMe[subscript 2]Ph)(Biphen) (Biphen = e.g., 3,3′-(t-Bu)[subscript 2]-5,5′-6,6′-(CH[subscript 3])[subscript 4]-1,1′-biphenyl-2,2′-diolate), while cis,syndiotactic poly(NBE) and poly(TCD) were prepared employing W-based imido or oxo monoaryloxide pyrrolide (MAP) initiators, W(X)(CHR′)(Pyrrolide)(OTer) (X = NR or O; OTer = a 2,6-terphenoxide). Addition of 1-hexene or coordinating solvents such as THF do not decrease the stereospecificity of the polymerization. Cis,iso and cis,syndio dyads can be distinguished through examination of [superscript 1]H and [superscript 13]C NMR spectra of the two polymers in a mixture. The polymers were hydrogenated to give isotactic and syndiotactic H-poly(NBE) and H-poly(TCD).