Nickel(II) complexes bearing pyrazolylimine ligand: synthesis, structure, and catalytic properties for vinyl-type polymerization of norbornene

Two nickel(II) complexes of {2‐[C3HN2(R1)2‐3,5]}[C(R2)N(C6H3iPr2‐2,6)]NiBr2 (complex 1: R1 = CH3, R2 = 2,4,6‐trimethylphenyl; complex 2: R1 = R2 = Ph) were synthesized and characterized. The solid‐state structure of complex 1 has been confirmed by X‐ray single‐crystal analysis. Activated by methyla...

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Published in:Applied organometallic chemistry 2010-04, Vol.24 (4), p.308-313
Main Authors: Wang, Yuan-yuan, Li, Ben-xia, Zhu, Yu-zhang
Format: Article
Language:English
Subjects:
nickel(II) complexes
norbornene
vinyl-type polymerization
X-ray single-crystal analysis
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Summary:Two nickel(II) complexes of {2‐[C3HN2(R1)2‐3,5]}[C(R2)N(C6H3iPr2‐2,6)]NiBr2 (complex 1: R1 = CH3, R2 = 2,4,6‐trimethylphenyl; complex 2: R1 = R2 = Ph) were synthesized and characterized. The solid‐state structure of complex 1 has been confirmed by X‐ray single‐crystal analysis. Activated by methylaluminoxane (MAO), complexes 1 and 2 are capable of catalyzing the polymerization of norbornene with moderate activities [up to 10.56 × 105 gPNBE (mol Ni h)−1] with high molecular weights (Mw⩽13.56 × 105 g mol−1) and molecular weight distributions were around 2. The influences of polymerization parameters such as reaction temperature and Al–Ni molar ratio on catalytic activity and molecular weight of the polynorbornene were investigated in detail. The obtained polynorbornenes were characterized by means of 1H‐NMR and FTIR techniques. The analytical results of polymer structures indicated that the norbornene polymerization is vinyl‐type polymerization rather than ROMP. Copyright © 2009 John Wiley & Sons, Ltd. Two nickel(II) complexes bearing pyrazolylimine ligand were synthesized and characterized; the solid‐state structure of complex 1 was confirmed by X‐ray single‐crystal analysis. Activated by methylaluminoxane, the two complexes are capable of catalyzing the polymerization of norbornene with moderate activities. The analytical results of polymer structures indicate that the norbornene polymerization is vinyl‐type polymerization rather than ROMP.
ISSN:0268-2605
1099-0739
DOI:10.1002/aoc.1603