Experimental and DFT study on titanium-based half-sandwich metallocene catalysts and their application for production of 1-hexene from ethylene

Different types of [Ind-C(R)-Phenyl]TiCl3 catalysts based on pendant arene containing indenyl (Ind) ligand bearing various bridges (R=cyclo‐C5H10 (C1), (CH3)2 (C2), 4-tBu-cyclo‐C5H9 (C3), and cyclo‐C6H12 (C4)) have been synthesized, used in the ethylene trimerization to 1-hexene presence methyl aluminoxane (MAO) as co-catalyst. The reaction conditions were first optimized C2 catalyst case, where highest product was achieved at concentration, temperature pressure 1.5× 10−3 M, 40 °C, 8 bar, respectively. During this optimization under specific conditions, a switching behavior from polymerization also detected, an undesired reaction. At synthesized showed following trend toward both yield selectivity: C1>C2>C3>C4. Then, shed light possible mechanisms confirm activity obtained experimental section, density functional theory (DFT) calculations employed. In line, results for simulation studies fit well with experiments. According DFT results, catalytic observed cyclohexane middle bridge (C1).