Evidence from ring-opening metathesis polymerization ROMP

4 Evidence from ring-opening metathesis polymerization (ROMP) 

With cycloocta-1,5-diene, reaction (10) can take place at any double bond in the chain, so accounting for the continuous series of cyclic oligomers of formula (C4He). At the beginning of the reaction, alternate double bonds in the chain P will have cis configuration (being pre-formed in the monomer) but the other double bonds may be cis or trans. It appears that this is not a significant factor in 

5 Evidence from the reactions of well-deflned metal carbene complexes 

Stable metal carbene complexes, such as W[=C(OMe)Me](CO)5, were first prepared by Fischer, E.O. (1964). These 18-electron complexes can be activated as catalysts for the metathesis of pent-l-ene or the ROMP of cycloalkenes by the use of a cocatalyst, or by heat or UV irradiation see Table 2.1. For such complexes to become active as initiators of olefin metathesis it is necessary for a CO ligand to be displaced, allowing the substrate to enter the coordination shell and react with the metal carbene bond. For the ROMP of 1-methyl-rrans-cyclooctene initiated by W(=CPh2)(CO)5 at 50°C the Ph2C= end groups may be detected in the polymer by the UV absorption at 245 nm (Lee, S.J. 1976). 

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