Stereoregular fluoropolymers: 5. The ring‐opening polymerization of 2‐trifluoromethylbicyclo‐[2.2.1]hepta‐2,5‐diene

2-Trifluoromethylbicyclo[2.2.1]hepta-2,5-diene undergoes metathesis ring-opening polymerization under the influence of the initiators WCl6/(CH3)4Sn, MoCl5/(CH3)4Sn, OsCl3, RuCl3, IrCl3 and ReCl5. Analysis of the infrared and high-field 13C-n.m.r. spectra of the different polymers leads to the following conclusions: the Mo based initiator gives predominantly trans-vinylene units; the Re based system shows the greatest tendency towards stereoregulation and gives predominantly cis-vinylenes; and the other catalysts are unselective in this respect. 2-Trifluoromethylbicyclo[2.2.1]hepta-2,5-diene is more readily polymerized than its 2,3-bis(trifluoromethyl) analogue; both monomers display no vinylene stereoselectivity with the very reactive W based initiator, whereas with both Mo and Ru based initiators the disubstituted monomer displays significantly greater trans-vinylene selectivity.