Abstract

© 2020 Elsevier B.V.Two new neutral N,N-indazole ligands bearing the carbonitrile functional group (L1 and L2) and two new air-stable cationic nickel methallyl complexes (C1 and C2) were prepared. These compounds were fully characterized by NMR, FT-IR and elemental analysis. In addition, compounds L1, L2 and C2 were analyzed using X-ray diffraction. The reactivity of complexes C1 and C2 toward ethylene was studied by using 5 equivalents of B(C6F5)3. At 12.5 bar of ethylene and 20 °C, complexes C1 and C2 could produce oligoethylenes with a moderate activity ∼ 700 kg of PE (mol of Ni)-1h−1. By increasing the temperature to 60 °C, the catalytic activity increased to ∼ 103 kg of PE (mol of Ni)-1h−1, and oligoethylenes were produced. The microstructure studied by 13C NMR revealed a broad distribution of branches, including methyl, ethyl, propyl, butyl and long branches. Remarkably, complexes C1 and C2 showed the presence sec-butyl branches, which are characteristic of hyperbranched microstructures. The GPC analysis result is consistent with the use of low-molecular-weight materials, and the PD1 was ∼ 1, which may indicate the presence of living behavior.