Synthesis of pentavalent imidovanadium complexes and their catalyses for the polymerization of ethylene and propylene

This is the authors' abstract. We don't add key points for this paper.

Imidovanadium complexes with cyclopentadienyl (Cp) ligands—(Cp)V(NC6H4Me‐4)Cl2 (1), (Cp)V(NtBu)Cl2 (2), and (tBuCp)V(NtBu)Cl2 (3; tBuCp = tert‐butylcyclopentadienyl)—were synthesized through the reaction of imidovanadium trichloride with (trimethylsilyl)cyclopentadiene derivatives. The molecular structure of 3 was determined by X‐ray crystallography. The monocyclopentadienyl complex 1 exhibited moderate activity in combination with methylaluminoxane [MAO; 10.3 kg of polyethylene (mol of V)−1 h−1 atm−1], whereas similar complexes with bulky tBu groups, 2 and 3, were less active. (2‐Methyl‐8‐quinolinolato)imidovanadium complexes, V(NR)(O ˆN)Cl2 (R = C6H3iPr2‐2,6 (4) or n‐hexyl (5), O ˆN = 2‐methyl‐8‐quinolinolato), were obtained from the reaction of imidovanadium trichloride with 2‐methyl‐8‐quinolinol. Upon activation with modified MAO, complex 4 showed moderate activities for the polymerization of ethylene at room temperature. The complex 5/MAO system also exhibited moderate activity at 0°C. The polyethylenes obtained by these complexes had considerably high melting points, which indicated the formation of linear polyethylene. Moreover, the 5/dried MAO system showed propylene polymerization activities and produced polymers with considerably high molecular weights and narrow molecular weight distributions.