Propylene polymerization with nickel-diimine complexes containing pseudohalides

• Published in: Journal of polymer science. Part A, Polymer chemistry Polymer chemistry, 2006-01, Vol.44 (1), p.458-466
• Main Authors: Dias, Marcos L., da Silva, Luciana P., Crossetti, Geraldo L., Galland, Griselda B., Filgueiras, Carlos A. L., Ziglio, Cláudio M.
• Format: Article
• Language: English
• Subjects: addition polymerization; Applied sciences; Exact sciences and technology; isoselenocyanate; isothiocyanate; isothiocyanate, nickel–diimine complexes; metal-organic catalyst/organometallic catalyst; nickel-diimine complexes; Organic polymers; Physicochemistry of polymers; poly(propylene) (PP); Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; propylene polymerization; pseudohalide ligands
• ISSN: 0887-624X; 1099-0518
• DOI: 10.1002/pola.21013

DADNiX2 nickel–diimine complexes [DAD = 2,6‐iPr2C6H3NC(Me)C(Me)N2,6‐iPr2C6H3] containing nonchelating pseudohalide ligands [X = isothiocyanate (NCS) for complex 1 and isoselenocyanate (NCSe) for complex 2] were synthesized, and the propylene polymerization with these complexes and also with the Br ligand (X = Br for complex 3) activated by methylaluminoxane (MAO) were investigated (systems 1, 2, and 3/MAO). The polypropylenes obtained with systems 1, 2, and 3 were amorphous polymers and had high molecular weights and narrow molecular weight distributions. Catalyst system 1 showed a relatively high activity even at a low Al/Ni ratio and reached the maximum activity at the molar ratio of Al/Ni = 500, unlike system 3. Increases in the reaction temperature and propylene pressure favored an increase in the catalytic activity. The spectra of polypropylenes looked like those of propylene–ethylene copolymers containing syndiotactic propylene and ethylene sequences. At the same temperature and pressure, system 2 presented the highest number of propylene sequences, and system 3 presented the lowest. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 458–466, 2006 New DADNiX2 nickel–diimine complexes [DAD = 2,6‐iPr2C6H3NC(Me)C(Me)N2,6‐iPr2C6H3] containing nonchelating pseudohalide ligands (X = isothiocyanate or isoselenocyanate) were prepared and applied to propylene polymerization with methylaluminoxane (MAO) and were compared with a known Br analogue. These catalyst systems produced high‐molecular‐weight amorphous propylene polymers with structures similar to those of propylene–ethylene copolymers containing moderately syndiotactic propylene sequences and ethylene sequences.