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Metallocene complexes with a cocatalyst such as methylalumoxane, MAO can be used as catalysts in the dimerization or oligomerization of olefins (alkenes) including the (co‐/hydro‐)oligomerization of ethene, of the α‐olefins propene, 1‐butene, 1‐pentene, 1‐hexene, and higher α‐olefins, branched α‐olefins, cyclic olefins and α,ω‐dienes. Possible applications of α‐olefin oligomers are summarized. Oligo‐olefins can be analyzed by gel permeation chromatography (GPC) or 1H NMR spectroscopy for molecular weight determinations and by 1H and 13C NMR spectroscopy or MALDI‐TOF mass spectrometry for their end group structure.

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The palladium(II) complex [Pd(C(6)F(5))Cl(bpzm*)] (5) [bpzm* = bis(3,5-dimethylpyrazol-1-yl)methane] was characterized by (1)H,(1)H-TOCSY, (1)H-NOE difference spectra, (1)H,(19)F-HOESY and (13)C,(1)H-HMBC 2D-NMR techniques. Chemical exchange of the methylene protons from (1)H,(1)H-NOESY cross peaks and exchange of the ortho- and meta-fluorine atoms, respectively, from (19)F,(19)F-EXSY cross peaks indicates that the Pd-bpzm* chelate ring boat-to-boat inversion occurs at a rate slower than the NMR time scale together with a concomitant change of the C(6)F(5) atom positions. The presence of three (19)F-NMR signals for 2F(o) : 1F(p) : 2F(m) of the C(6)F(5) ligand for complexes [Pd(C(6)F(5))Cl(tmeda)] (1) and [Pd(C(6)F(5))Cl(bipy)] (3) (tmeda = N,N,N',N'-tetramethylethylenediamine; bipy = 2,2'-bipyridine) is interpreted as being due to identical hemi-spaces above and below an apparent symmetry plane coinciding with the Pd-coordination plane instead of free ring rotation. The molecular structures of 1, 3 and 5 from single-crystal studies suggest that the hindered C(6)F(5) rotation is not limited to 5 but is also present in 1 and 3 due to ligand repulsion. Complexes [Pd(C(6)F(5))Cl(tmeda)] (1), [Pd(C(6)F(5))OH(tmeda)] (2), [Pd(C(6)F(5))Cl(bipy)] (3), [Pd(C(6)F(5))OH(bipy)] (4) and [Pd(C(6)F(5))Cl(bpzm*)] (5) have been applied as pre-catalysts for the vinyl homopolymerization of norbornene in combination with the cocatalyst methylaluminoxane (MAO). Activities of more than 10(6) g(polymer)/(mol(Pd) h) could be reached with these catalytic systems. Based on the spectrochemical series, pre-catalysts 1 and 2 with the pure sigma-donor and more weakly bound aliphatic amine ligands showed higher polymerization activities than compounds 3-5 with modest pi-accepting and stronger bound aromatic substituents. This is reasoned with a kinetic activation effect through a faster removal of the more weakly bound ligands upon reaction with MAO together with the chloro or hydroxo ligands to give the active, almost "naked" Pd(2+) cations. For the activation mechanism, (1)H-, (13)C- and (19)F-NMR studies of the MAO activated complex 5 showed about 13% chlorine-to-methyl exchange for a molar Pd : Al ratio of 1 : 10. For 5 : MAO at a Pd : Al ratio of 1 : 100 abstraction of C(6)F(5) takes place with a redox reaction giving Pd metal and C(6)F(5)-CH(3) in the absence of norbornene monomer.