Kinetic study of the ring-opening metathesis polymerization of ionically functionalized cyclooctatetraenes

The ring-opening metathesis polymerizations of alkylammonium and sulfonate functionalized cyclooctatetraenes (RCOT, R = CH(2)CH(2)SO(3)TMA or CH2CH2NMe3OTf, OTf = CF3SO3-, TMA = Me4N+) with the well-defined tungsten catalyst W=CH(o-C6H4OMe)(NC6H5)[OCCH3(CF3)(2)](2)(THF) (THF = tetrahydrofuran) were investigated. The polymerizations exhibited first-order decay in monomer concentration and slow initiation relative to propagation, and for COTCH(2)CH(2)SO(3)TMA where studies were possible, molecular weights largely independent of the extent of the reaction and initial reaction conditions. The central kinetic feature was the observation of a pseudo-first-order rate constant inversely proportional to the initial monomer concentration, suggesting some form of inhibition. Furthermore, the polymerization of COTCH2CH2NMe3OTf is inhibited by the addition of TBAOTf (TBA = Bu4N+). The apparent inhibition is discussed in terms of the potential for ion pairing or anion coordination to the catalyst center.