Coordination Polymerization of Renewable (E)‐4,8‐Dimethyl‐1,3,7‐Nonatriene by Rare‐Earth Metal Catalysts

Comprehensive Summary Coordination polymerization of renewable ( E )‐4,8‐dimethyl‐1,3,7‐nonatriene (DMNT) has been performed using pyridyl‐methylene‐ fluorenyl scandium complex 1, half‐sandwich scandium complex 2, diiminophosphinato rare‐earth metal complexes 3a—3c and 4a—4b, bis(phosphino)carbazolide yttrium complex 5 and β‐diketiminato yttrium complex 6. Fluorenyl scandium complexes 1 and 2, activated by [Ph 3 C][B(C 6 F 5 ) 4 ] and Al i Bu 3 , are moderately active and show perfect 1,2‐regioselective (1,2 > 99%). Conversely, asymmetric diiminophophinato complexes 3a—3c promote the DMNT polymerization to produce high trans ‐1,4 regulated products with the activity trend: Sc < Lu < Y. Complexes 4—6 are virtually inactive for the DMNT polymerization although they are highly active in isoprene polymerization. A diblock copolymer bearing 3,4‐polyisoprene block and trans ‐1,4‐poly(DMNT) block is obtained using complex 3c in one‐pot reaction. Hydrogenation of trans ‐1,4‐poly(DMNT) affords an elastomer with a T g of –10°C. The epoxidation reaction of trans ‐1,4‐poly(DMNT) with 3‐chloroperbenzoic acid transfers the pendant double bonds in the cis configuration into the epoxy groups.