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The cobalt(II) chloride <i>N,N,N</i>-pincer complexes, [2-{(2,4-(C₁₅H₁₃)₂-6-FC₆H₂)N=CMe}-6-(ArN=CMe)C₅H₃N]CoCl₂ (Ar <b>=</b> 2,6-Me₂C₆H₃) (<b>Co1</b>), 2,6-Et₂C₆H₃ (<b>Co2</b>), 2,6-<i>i</i>-Pr₂C₆H₃ (<b>Co3</b>), 2,4,6-Me₃C₆H₂ (<b>Co4</b>), 2,6-Et₂-4-MeC₆H₂ (<b>Co5</b>), and [2,6-{(2,4-(C₁₅H₁₃)₂-6-FC₆H₂)N=CMe}₂C₅H₃N]CoCl₂ (<b>Co6</b>), each containing at least one <i>N</i>-2,4-bis(dibenzosuberyl)-6-fluorophenyl group, were synthesized in good yield from their corresponding unsymmetrical (<b>L1</b>–<b>L5</b>) and symmetrical bis(imino)pyridines (<b>L6</b>). The molecular structures of <b>Co1</b> and <b>Co2</b> spotlighted their distorted square pyramidal geometries (<i>τ</i>₅ value range: 0.23–0.29) and variations in steric hindrance offered by the dissimilar <i>N</i>-aryl groups. On activation with either MAO or MMAO, <b>Co1</b>–<b>Co6</b> all displayed high activities for ethylene polymerization, with levels falling in the order: <b>Co1</b> > <b>Co4</b> > <b>Co5</b> > <b>Co2</b> > <b>Co3</b> > <b>Co6</b>. Indeed, the least sterically hindered 2,6-dimethyl <b>Co1</b> in combination with MAO exhibited a very high activity of 1.15 × 10⁷ g PE mol⁻¹ (Co) h⁻¹ at the operating temperature of 70 °C, which dropped by only 15% at 80 °C and 43% at 90 °C. Vinyl-terminated polyethylenes of high linearity and narrow dispersity were generated by all catalysts, with the most sterically hindered, <b>Co3</b> and <b>Co6</b>, producing the highest molecular weight polymers [<i>M</i>_w range: 30.26–33.90 kg mol⁻¹ (<b>Co3</b>) and 42.90–43.92 kg mol⁻¹ (<b>Co6</b>)]. In comparison with structurally related cobalt catalysts, it was evident that the presence of the <i>N</i>-2,4-bis(dibenzosuberyl)-6-fluorophenyl groups had a limited effect on catalytic activity but a marked effect on thermal stability.