A set of structurally modulated salicylaldimine cobalt(II) complexes have been synthesized and utilized them for ethylene oligomerizations in combination with various organoaluminum cocatalysts. All catalyst systems yielded a-olefins with butenes as major product. The catalytic activity and product distribution were affected by the catalytic structure and reaction conditions. The formation of active species in these complexes under oligomerization conditions was investigated by UV-VIS spectroscopy and the results matched well with oligomerization results.

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We have performed copolymerizations of ethylene with 1-hexene using various ansa-metallocene compounds in the presence of the non-coordinative [CPh 3 ][B(C 6 F 5 ) 4 ] ion pair as a cocatalyst. The metallocenes chosen for this study are isospecific metallocene diamide compounds, rac-(EBI)Zr(NMe 2 ) 2 [1, EBI = ethylene-1,2-bis(1-indenyl)], rac-(EBI)Hf(NMe 2 ) 2 (2), rac-(EBI)Zr(NC 4 H 8 ) 2 (3), and rac-(CH 3 ) 2 Si(1-C 5 H 2 -2-CH 3 -4-t C 4 H 9 ) 2 Zr(NMe 2 ) 2 (4), and syndiospecific metallocene dimethyl compounds, ethylidene(cyclopentadienyl)(9-fluorenyl) ZrMe 2 [5, Et(Flu)(Cp)ZrMe 2 ] and isopropylidene(cyclopentadienyl)(9-fluorenyl)ZrMe 2 [6, iPr(Flu)(Cp)ZrMe 2 ]. The copolymerization rate decreased in the order 4 > 1 ~ 3 > 2 > 5 > 6. The reactivity of 1-hexene decreased in the order 2 > 6 > 1 ~ 3 ~ 5 > 4. We characterized the microstructure of the resulting poly(ethylene-co-1-hexene) by 13 C NMR spectroscopy and investigated various other properties of the copolymers in detail.

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