Copolymerization of Carbon Monoxide with Alkenes - Late Transition Metal Polymerization Catalysis - page 294

Scheme 8.17 Attempted rationalization of the higher catalytic activity of the meso -
vs. the rac -ligand for carbon monoxide-propene copolymerization.

nation using catalysts modified with 81 , 82 and 90 . In particular for the regiospecific
systems 82 and 90 , the optical activity of the terpolymers normalized to the propene
content changes only very little with respect to the copolymers obtained with the
same precursors catalyst, thus showing an overwhelming enantiosite control [123].
Various copolymers and terpolymers poly(ketone)s containing functional groups
(phenolic or phenyl ether substrates) were prepared using [Pd(dppp)(CH 3 CN) 2 ]
(BF 4 ) 2 as the catalyst precursor [124, 125]. Using the same catalytic system meso-
genic 1-alkenes were also copolymerized [126].

8.6
Copolymerization of Internal and Cyclic Olefins

The copolymerization of internal olefins has received little attention, probably due
to the lack of catalytic activity of the systems discussed so far. Only results con-
cerning ( Z )-2-butene have been reported. Using the Me-Duphos-modified catalyst
86 (Scheme 8.16), a poly[1-oxo-2-methyl-1,4-butanediyl] (Scheme 8.18) formed

with low molecular weight (mean oligomerization degree 7) [32].

The optical activity of the material suggested a prevailingly isotactic structure. Sim-
ilarly cyclopentene has received little attention [127]. This substrate gives copolymers
with a prevailingly 1,3-enchainment with respect to the normal 1,2-enchainment.
The best regioselectivity ( 95%) was obtained using ( R , R )-[bicyclo[2.2.2]octane-

3,4-diylbis(methylene)]bis(diphenylphosphine) as the modifying ligand. However,
the largest molar masses (up to 8500) were obtained when the copolymers showed
the greatest extent of 1,2-enchainment. A prevailingly diisotactic structure has been
suggested for the copolymers giving the most simple NMR spectra.