| Abstract |
Reaction between 3-((1R,2R)-2-\[1-(3,5-di-tert-butyl-2-hydroxy-phenyl)-meth-(E)-yliden e]-amino\-cyclohexyl)-1- isopropyl-4-phenyl3H- imidazol-1-ium bromide (1a) or the derivative 3-((1R,2R)-2-\[ 1-(2-hydroxy-5-nitro-phenyl)-meth-( E)- ylidene]- amino\- cyclohexyl)1- isopropyl- 4-phenyl-3H-imidazol-1-ium bromide (1b) and metal halides MCl(x center dot)yTHF (M = Zr, x = 4, y = 2; M= V, x = y = 3; M = Cr, x = y = 3), in THF, at -78 degrees C gives the metal complexes of general formula [ MCl(x)(kappa(2)-N, O-OC(6)H(2)R(1)R(2) C( H)= N-C(6)H(10)-Im) 2][Br](2) ( where M = Zr, x = 2, R(1)= R(2) = (t)Bu, 2; M = Zr, x = 2, R(1)= H, R(2)= NO(2), 3; M= V, x = 1, R(1)= R(2) = (t)Bu, 4; M = Cr, x = 1, R(1)= R(2) = (t)Bu, 5; M = Fe, x = 0, R(1)= R(2) = (t)Bu, 6; Im = 1-isopropyl-4-phenyl-3H-imidazol-1-ium-3-yl). 1 H and (13)C NMR spectroscopy of 2 and 3 indicate kappa(2)- N, O-ligand coordination via the phenoxy-imine moiety with pendant imidazolium salt that is corroborated by a single crystal structure of 6. Compounds 2, 3, 4 and 5 were tested as precatalysts for ethylene polymerisation in the presence of methylaluminoxane (MAO) cocatalyst, showing low activity. Selected polymer samples were characterised by GPC showing multimodal molecular weight distributions. (c) 2007 Elsevier B. V. All rights reserved. |
