Oligomerisation of 1-pentene with metallocene catalysts

The homo-oligomerisation of l-pentene in the presence of various bridged an d non-bridged metallocenes and methylaluminoxane (MAO) at room temperature and at 60 degrees C, respectively, has been studied. The use of the bridged catalysts rac-[C2H4(Ind)(2)]ZrCl2 (1) and [(CH3)(2)Si(Ind)]ZrCl2 (2) leads to the formation of isotactic poly(l-pentene). The use of Cp2ZrCl2 (3), Cp 2HfCl2 (4) and [(CH3)(5)C-5](2)ZrCl2 (5) leads to the formation of atactic poly(l-pentene). The stereoregularity of the isotactic poly(l-pentene) obta ined with 1 was higher than that of the poly(l-pentene) synthesised with 2. The degree of polymerisation was highly dependent on the metallocene catal yst. Oligomers ranging from the dimer of l-pentene to poly(l-pentene) with a number-average molar mass M-n = 5100 g mol(-1) were formed. The H-1 NMR s pectra of the samples were analysed with regard to functional groups and th ese were attributed to different chain termination processes. A MALDI-TOF s pectrum of low-molar-mass poly(l-pentene) could be recorded using dithranol as matrix and adding silver trifluoroacetate to promote ion formation.