Isospecific Oligo-/Polymerization of Styrene with Soluble Cationic Nickel Complexes. The Influence of Phosphorus(III) Ligands
| Autor: | Carlos C. Romão, Igor Tkatchenko, André Revillon, Pedro T. Gomes, and Alberto R. Dias, José R. Ascenso, Quang-Tho Pham |
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| Rok vydání: | 1996 |
| Předmět: |
Polymers and Plastics
010405 organic chemistry Chemistry Ligand Organic Chemistry Cationic polymerization Regioselectivity Homogeneous catalysis 010402 general chemistry 01 natural sciences 0104 chemical sciences Styrene Inorganic Chemistry End-group chemistry.chemical_compound Monomer Polymerization Polymer chemistry Materials Chemistry |
| Zdroj: | Macromolecules. 29:4172-4179 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/ma950930g |
| Popis: | The influence of several phosphorus(III) ligands upon the activity and the stereoregulation ability of the soluble organometallic complex [Ni(η3-(2-methylallyl))(η4-COD)]PF6 (COD = 1,5-cyclooctadiene), 1, is studied. There is a general increase of the catalytic activity which can be associated with the P(III) ligand's lability. A detailed analysis of the mass distribution and microstructure is carried out by GPC and 1H and 13C NMR of the solvent-fractionated polymers. In the majority of cases, regioregular low molecular weight polymers with the structure PhCHCH2[CH(Ph)CH2]nCH(Ph)CH3 are obtained. The addition of bulky phosphines, such as P(o-Tol)3 (o-Tol = o-tolyl) and PCy3 (Cy = cyclohexyl), affords highly isotactic oligomers (≈90%). For the latter, the regioselectivity of the chain growth is broken during the insertion of the last monomer, which results in the formation of a tail-to-tail end group, CH2C(C6H5)CH(C6H5)CH2−. The superimposed effects of η3-coordination of the chain end and the large stereoc... |
| Databáze: | OpenAIRE |
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