ACYCLIC DIENE METATHESIS (ADMET) POLYMERIZATION USING A WELL-DEFINED RUTHENIUM BASED METATHESIS CATALYST

A series of alpha,omega-dienes have been exposed to Ru(Cl-2)(CH=Ph)(PC y(3))(2), [Ru] 3, metathesis catalyst under acyclic diene metathesis ( ADMET) conditions, and the products were compared with those obtained previously using Schrock's well defined Mo and W alkylidenes. High mol ecular weight polymers can be synthesized using [Ru] 3 if lower monome r to catalyst ratios (with respect to [Mo] 1 and [W] 2 are used. Monom er structure plays a role since 1,9-decadiene produces molecular weigh ts typical of ADMET chemistry, whereas 1,5-hexadiene produces only oli gomers. This decrease in reactivity is attributed to a manifestation o f intramolecular pi-complexation of the tethered olefin in 1,5-hexadie ne polymerizations. Substituents at the 2-position of alpha,omega-dien es also affects polymerization in that only dimers can be produced fro m 2-methyl-1,5-hexadiene, a result similar to the same reaction perfor med with [W] 2. Diallyl ether oligomerizes effectively in the presence of [Ru] 3 with a ratio of cyclics to oligomers comparable to results obtained with [Mo] 1 and [W] 2.