Living/controlled hex-1-ene polymerization initiated by nickel diimine complexes activated by non-MAO cocatalysts: Kinetic and UV–vis study

Abstract Living/controlled polymerization of hex-1-ene initiated by nickel diimine catalysts of general form [ArN=C(1,8-naphthalenediyl)C=NAr]NiBr 2 activated by simple organoaluminium compounds was investigated. Polyhexenes with a very narrow molar mass distribution and molar mass controlled by the monomer/initiator ratio were prepared using diethylaluminiumchloride, ethylaluminiumdichloride and methylaluminiumdichloride as cocatalysts for nickel complexes 1 (Ar = 2,6-iPr 2 C 6 H 3 ) and 2 (Ar = 2-tBuC 6 H 4 ). Nickel complexes with smaller aryl substituents ( 3 , Ar = 2,6-Me 2 C 6 H 3 ; 4 Ar = 2,4,6-Me 3 C 6 H 2 ; 5 , Ar = 2,6-Et 2 C 6 H 3 ) undergo transfer reactions significantly. For the most bulky complex 1 activated by ethylaluminiumdichloride living hex-1-ene polymerization was achieved, proved by the reinitiation of polymer growth upon the addition of fresh monomer. The effect of Al/Ni ratio on the activity of the catalytic systems was studied by dilatometry. The catalytic systems were investigated by UV–vis spectrometry and a new interpretation of their absorption spectra was suggested.