A set of new chromium(III) [Cr(III)] complexes based on the tridentate ligand HC(Pz)2Py (Pz = pyrazole; Py = pyridine) and its derivatives were prepared, characterized, and evaluated for ethylene polymerization/oligomerization. X-ray single-crystal analyses of the Cr(III) complexes showed tridentate coordination on the fac-octahedral Cr sphere. Upon activation with methylaluminoxane (MAO), the precatalysts and the ligands L1-L3 mixed in situ with Cr(acac)3 were highly active and generally produced polyethylene as a major product. Their catalytic performances were markedly affected by the substituents on the methine carbon atom of the ligands and reaction conditions.

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In the title compound, C 13 H 13 N 5 , the planes of the pyrazolyl groups are nearly perpendicular to that of the central pyridine ring, making dihedral angles of 87.77 (8) and 85.73 (7) . In the crystal, weak C-HÁ Á ÁN hydrogen bonds link the molecules into layers extending parallel to (101).