New chromium(III) [Cr(III)] catalysts based on 2,6-bis(pyrazol-1-ylmethyl) pyridine derivatives have been synthesized, characterized, and evaluated for ethylene polymerization. All ligands with sub-stituents on the pyrazole rings were analyzed by single-crystal X-ray diffraction to clearly identify isomer structures. Additionally, X-ray analyses of the new Cr(III) complex bearing 2,6-bis[(4,5-dimethyl-1H-pyrazol-1-yl) methyl]pyridine showed tridentate coordination on the mer-octahedral chromium sphere. Upon activation with dry methyaluminoxane, the precatalysts produce polyethylene (PE) as a major product, and their catalytic performances were affected by the substituents on the pyrazole units; the introduction of functional groups on the pyrazole raised PE compositions and the molecular weight of the PE. (C) 2015 Elsevier B.V. All rights reserved.