Styrene polymerization with nickel complexes/methylaluminoxane catalytic system

Polymerization of styrene using beta-diketiminate nickel (II) bromide complexes CH{C(R)NAr}(2)NiBr (R = CH3, Ar = 2,6-(Pr2C6H3)-Pr-i, 1; R = CH3, Ar = 2,6-Me2C6H3,2; R = CF3, Ar = 2,6-(Pr2C6H3)-Pr-i,3; R = CF3, Ar = 2,6-Me2C6H3,4) 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 21000 to 72 000, with polydispersity indexes of 1.95-2.78. The microstructure of the obtained products is atactic polystyrenes from NMR analyses. Copyright (C) 2008 John Wiley & Sons, Ltd.