Tris(pyrazolyl)methane–chromium(III) complexes as highly active catalysts for ethylene polymerization

Switching from ethylene polymerization to nonselective oligomerization over a homogeneous model catalyst: A triphenylsiloxy complex of chromium(VI)

“…Conversely, the M w values of the low molecular weight fraction decreased with the Al/Cr molar ratio increasing, and their corresponding PDI were found to be in the range from 1.1 to 1.6 (Table 2, entries 5e8). Similar bimodal MWD of PE was also reported recently for a tris(pyrazolyl)methane-chromium(III) complex with MAO as the cocatalyst [24]. The T m values ( Table 2, entries 1e2, 4e5) of the PE are similar to that of HDPE around 132 C. As for BC/MAO system, increasing the Al/Cr molar ratio led to a slightly decrease in the T m values, which can be explained by the introduction of some branching to PE chains arising from the in-situ copolymerization of the obtained oligomers with ethylene.…”

Water‐Soluble C‐Scorpionate Complexes – Catalytic and Biological Applications

“…The hydroxymethylene derivative 2,2,2‐tris(pyrazol‐1‐yl)ethanol [HOCH 2 C(pz) 3 , Tpm OH 3 ], obtained by carbon functionalization of Tpm (Scheme ),, represents a sort of “chemical scaffold” for the development of a synthetic plan for further functionalizations, as the reactivity of the alkoxide prepared upon the deprotonation of the Tpm OH is a more versatile scaffold than the carbanion derived from Tpm. The preparation of Tpm OH involves a mild deprotonation of the apical methine carbon atom with an appropriate base and the subsequent nucleophilic attack of paraformaldehyde.…”

Cr Complexes of Nitrogen Donor Ligands for Olefin Oligomerisation and Polymerisation

“…Complexes of structure 33 lead to very high activities, up to 2,500 kg mol Cr -1 bar -1 h -1 , following MAO activation [42]. A bimodal distribution of polyethylene is normally formed in which a low molecular weight fraction (M n = 1,500 g mol -1 ) is predominant.…”