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Cyclopolymerization of Nonconjugated Dienes with a Tridentate Phenoxyamine Hafnium Complex Supported by an sp 3 ‐C Donor: Isotactic Enchainment and Diastereoselective cis ‐Ring Closure
Author(s) -
Edson Joseph B.,
Coates Geoffrey W.
Publication year - 2009
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200900422
Subject(s) - tacticity , cyclopentane , methylene , monomer , diastereomer , metallacycle , cyclobutane , polymer chemistry , decalin , chemistry , polymer , ring (chemistry) , stereochemistry , medicinal chemistry , polymerization , catalysis , organic chemistry , x ray crystallography , physics , diffraction , optics
Cyclopolymerization of nonconjugated dienes produces poly(methylene‐1,3‐cycloalkanes) and provides a pathway to a number of stereochemically complex polymers. Activation of a diastereomeric mixture of a six‐membered metallacycle complex ( rac ‐ 1 ) in the presence of 1,5‐hexadiene produced poly(methylene‐1,3‐cyclopentane) (PMCP) with >98% cyclization of the diene monomer. The catalyst was found to cyclopolymerize 1,5‐hexadiene with relatively high activity. The microstructure of the PMCP furnished by rac ‐ 1 was found to contain a high proportion of cis ‐cyclopentane rings ( σ = 0.70–0.74) and a relatively high isotactic content ( α = 0.93–0.96). These are the first cis ‐enriched isotactic cyclopolymers of 1,5‐hexadiene. Cyclopolymerization of 1,6‐heptadiene with rac ‐ 1 /B(C 6 F 5 ) 3 produced poly(methylene‐1,3‐cyclohexane) containing 97% cis ‐isotactic rings. This is the first report of this highly isotactic and diastereomerically‐pure microstructure.