A homogeneous catalytic system based on a suitable Ni(II) diimine derivative and methylaluminoxane affords predominantly syndiotactic polypropylene at subambient temperatures. The polymer microstructure is that expected for a ''chain-end'' mechanism of steric control. NMR analysis of polymer samples carrying selectively C-13-enriched end groups indicates a largely prevailing 1,2 regiochemistry for the insertion of propene into Ni-(CH3)-C-13 bonds in the initiation step and a syndiotactic steric control already effective in the second propagation step.
Syndiotactic-specific polymerization of propene with nickel-based catalysts .2. Regiochemistry and stereochemistry of the initiation steps
PELLECCHIA, Claudio;ZAMBELLI, Adolfo;OLIVA, Leone;
1996
Abstract
A homogeneous catalytic system based on a suitable Ni(II) diimine derivative and methylaluminoxane affords predominantly syndiotactic polypropylene at subambient temperatures. The polymer microstructure is that expected for a ''chain-end'' mechanism of steric control. NMR analysis of polymer samples carrying selectively C-13-enriched end groups indicates a largely prevailing 1,2 regiochemistry for the insertion of propene into Ni-(CH3)-C-13 bonds in the initiation step and a syndiotactic steric control already effective in the second propagation step.File in questo prodotto:
Non ci sono file associati a questo prodotto.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.