Exploring the Reactivity of Na[W(2)(μ-Cl)(3)Cl(4)(THF)(2)]∙(THF)(3) towards the Polymerization of Selected Cycloolefins

The bimetallic compound Na[W(2)(μ-Cl)(3)Cl(4)(THF)(2)]·(THF)(3) (1, {W( 3 )W}(6+), a′(2)e′(4)) is a highly efficient room-temperature initiator for ring opening metathesis polymerization (ROMP) of norbornene (NBE) and some of its derivatives. In most cases, addition of phenylacetylene (PA) as co-initiator improves the catalytic activity and retains the high cis-stereoselectivity. On the other hand, 1 can polymerize cyclopentadiene (CPD), not via a metathetic, but rather, via a cationic mechanism. Here, we present a comparison of the reactivity of the two catalytic systems (1 and 1/PA) between themselves and with other systems reported in the literature, the characterization of the polymers formed and mechanistic aspects of the corresponding reactions.