Addition polymers of strained cyclic olefins - Transition metal catalysed polymerisations of the cyclobutene derivative bicyclo[3.2.0]hept-6-ene

Bicyclo[3.2.0]hept-6-ene was converted into the corresponding addition polymer poly(6,7-bicyclo[3.2.0]heptylene) with the aid of early and late transition metal based olefin polymerisation catalysts. Moderate to very good yields (42-99%) of polymer were obtained with [Pd(NCEt)(4)][BF4](2), [(eta(3)-allyl)Pd(solv(2))(2)][SbF6], [(2,9-dimethyl-1,10-phenanthroline)Pd(CH3)(NC(CH2)(6)CH3)][SbF6], and Cp2ZrCl2/MAO, using monomer to transition metal ratios between 50/1 and 250/1. Reaction occurs at the olefin pi-bond, and the four-membered ring of the monomer is retained during polymerisation which differs from ring-opening olefin metathesis polymerisation in which the four-membered ring is opened. The nearly exclusively saturated structure of the polymer was confirmed by H-1 and C-13 NMR spectroscopy. It is proposed that the polymers consist of repeating units that are predominantly cis-exo-enchained. GPC analysis of the soluble polymers prepared with [Pd(NCEt)(4)][BF4](2) showed that molecular mass values (M) over bar (n)(GPC) were in the range of 3 700 to 22 600.