Novel nickel (II) complexes chelating β‐diketiminate ligands: synthesis and simultaneous polymerization and oligomerization of ethylene

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Polymerization of styrene using β-diketiminate nickel (II) bromide complexes CH{C(R)NAr} 2 NiBr (R = CH 3 , Ar = 2,6-i Pr 2 C 6 H 3 , 1; R = CH 3 , Ar = 2,6-Me 2 C 6 H 3 , 2; R = CF 3 , Ar = 2,6-i Pr 2 C 6 H 3 , 3; R = CF 3 , Ar = 2,6-Me 2 C 6 H 3 , 4) in the presence of methylaluminoxane was studied. Compound 3 is the most active styrene polymerization catalyst of all the nickel complexes tested. The activity of these catalysts increases with increases in steric bulk of the substituents on the aryl rings. The electronic nature of the ligand backbone also affects the activity. Weight-average molecular weight of the prepared polystyrene ranges from 21 000 to 72 000, with polydispersity indexes of 1.95-2.78. The microstructure of the obtained products is atactic polystyrenes from NMR analyses.

Section: Polymerization Of Styrenesupporting

confidence: 90%

“…This result is consistent with substituent effect reported in ethylene and norbornene polymerization with these catalytic systems. [29,30] www.interscience.wiley.com/journal/aoc…”

Section: Polymerization Of Styrenementioning

confidence: 99%

Styrene polymerization with nickel complexes/methylaluminoxane catalytic system

Li¹,

Gao²,

Wu³

2008

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“…The initial [H 2 O]/[ TMA] molar ratio was 1.3 . The β‐diketiminate ligands and corresponding nickel complexes were prepared according to our previous method . Other commercially available reagents were purchased and used without purification.…”

Section: Methodsmentioning

confidence: 99%

Copolymerization of styrene and norbornene with β‐diketiminato nickel/methylaluminoxane catalytic system

Min-yu

et al. 2012

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Styrene-norbornene (S-N) copolymerizations were carried out using b-diketiminato nickel complexes CH{C(CF 3 )NAr} 2 NiBr (Ar = 2,6-i Pr 2 C 6 H 3 , 1; Ar = 2,6-Me 2 C 6 H 3 , 2) in the presence of methylaluminoxane. The influence of the comonomer feed content and polymerization temperature on the conversion and composition of the copolymers with the catalytic system was investigated. An increase in the feed ratio of S/N led to an increase in the incorporated styrene content of the resulting copolymer. NMR characterization of the copolymers generated with the catalytic systems showed that the random S-N copolymers are produced. Differential scanning calorimetric determination of the copolymers shows higher T g values than polystyrene, and gel permeation chromatographic measurements have shown that the copolymers possess rather narrow molecular weight distributions, suggesting that the copolymerization take place at a single active site.

“…Complexes with different sunstituents on the ligands backbone and different ortho-aryl substituents at nitrogen thus allowed us to investigate the effects of sterics and electronic properties of the ligand environment on norbornene polymerization. β-diketiminate ligands L1,L2 and their nickel complexes 1, 2, 30 as well as the fluorinated β-diketiminate ligands L3,L4 and their nickel complexes 3, 4 31 have been reported previously.…”

Section: Introductionmentioning

confidence: 65%

Vinyl polymerization of norbornene by nickel(II) complexes bearing β‐diketiminate ligands

Gao

2007

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Norbornene polymerizations were carried out using nickel(II) bromide complexes CH{C(R)NAr} 2 NiBr (1, R = CH 3 , Ar = 2, 6− i Pr 2 C 6 H 3 ; 2, R = CH 3 , Ar = 2, 6-Me 2 C 6 H 3 ; 3, R = CF 3 , Ar = 2, 6− i Pr 2 C 6 H 3 ; 4, R = CF 3 , Ar = 2, 6-Me 2 C 6 H 3 ) in the presence of methylaluminoxane. Compound 3 is the most active norbornene polymerization catalyst of all the nickel complexes tested. The activity of theses catalysts increases with increases in steric bulk of the substituents on the aryl rings. The electronic nature of the ligand backbone also affects the activity. The resulting polynorbornenes are vinyl type by IR and NMR analyses.