Syndioselective Ring-Opening Metathesis Polymerization of <i>e</i><i>ndo</i>-Dicyclopentadiene with Tungsten Complexes Having Imido Ligands: Development of Crystalline Syndiotactic Hydrogenated Poly(<i>e</i><i>ndo</i>-dicyclopentadiene)

Abstract

Tungsten-based catalysts induced syndioselective ring-opening metathesis polymerization (ROMP) of endo-dicyclopentadiene (DCPD) to produce a new class of crystalline polymer. Various tungsten(VI) imido chloride complexes of the type W(N−R)Cl4·(Et2O)n (R = Ph, 2,6-Me2Ph, α-naphthyl, 2,6-i-Pr2Ph, Et, n-Bu, n-Hex, cyclohexyl, adamantyl; n = 0 or 1) were prepared, which in combination with Et2Al(OEt) efficiently induced ROMP of DCPD. W(N−Ph)Cl4·Et2O and W(N−Et)Cl4·Et2O promoted cis- and syndioselective ROMP of DCPD, and the following hydrogenation provided a new crystalline polymer, syndiotactic hydrogenated poly(DCPD), which was characteristic in high melting point and in high crystallinity (Tm = 270 °C, ΔH = 52 J/g, wc = 0.61). The syndioselectivity of the polymerization could be controlled in the range 30−80% by the suitable choice of those tungsten imido catalysts. These are the first examples of well-designed binary catalysts that are effective in the syndioselective ROMP of DCPD.