The series of ligands 2-(1-(arylimino)methyl)-8-(1H-benzimidazol-2-yl)quinolines was synthesized and used to prepare new iron(II) and cobalt(II) dichloride complexes. X-ray diffraction studies revealed that the coordination geometry around the metal center can best be described as distorted square-based pyramidal. Upon activation with methylaluminoxane (MAO), both families (Fe and Co) of complexes showed good activities in ethylene polymerization, affording highly linear polyethylenes. Enhanced activities were observed on increasing the reaction temperature to 100 °C. The optimization of the reaction parameters and the influence of the substituents on the imino-bound aryl group of the chelate ligands were investigated.