Homogeneous polymerization of norbornene catalyzed by ruthenium complex–tertiary phosphine system

Norbornene is polymerized by ruthenium complex–tertiary phosphine catalysts to polymers consisting of trans‐and cis‐olefinic groups and 1,3‐cyclopentylene group. The system derived from dichloro(dodeca‐2,6,10‐triene‐1, 12‐diyl)ruthenium‐(IV) (1) and triphenylphosphine has a fairly high activity for the polymerization, while I itself has only a very low activity. The system derived from dichlorodi‐μ‐chlorobis‐(2,7‐dimethylocta‐2,6‐diene‐1,8‐diyl)diruthenium(IV) (II) and more moles of triphenyl‐phosphine than four shows almost the same activity as the I‐triphenylphosphine system does. However, II and dichloro(2,7‐dimethylocta‐2,6‐diene‐1,8‐diyl)‐(triphenylphosphine)ruthenium(IV) each polymerizes norbornene in a very high yield, in contrast with I. In addition, both dichlorotris(triphenylphosphine)ruthenium(II) and dichlorotetrakis(triphenylphosphine)ruthenium(II) have been found to display a considerably high activity for polymerization of norbornene. On the basis of these facts and the NMR data of the I– and II–triphenylphosphine systems, the mechanism for the polymerization of norbornene has been discussed.