K. Brzezinska et al., ACYCLIC DIENE METATHESIS (ADMET) POLYMERIZATION USING A WELL-DEFINED RUTHENIUM BASED METATHESIS CATALYST, Macromolecular chemistry and physics, 197(6), 1996, pp. 2065-2074
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.