Syntheses and Preferred Structure Elucidation of N ‐heterocyclic Imine Nickel and Cobalt Catalysts for MMA Polymerization

Here, L1 (2-(pyridin-2-yl)quinoxaline) and L2 ((1-((1 H-pyrrol-2-yl)ethylidene)benzene-1,2-dia mine) center dot (1-(1H-pyrrol-2-yl)ethanone)) were synthesized and reacted with CoCl2 center dot 6H(2)O and NiCl2 center dot 6H(2)O to produce complexes 1-4. We found several interesting pieces of crystal structure information. Firstly, ligands L1 and L2 with completely different molecular structures were obtained by reacting the precursors containing similar N-heterocycles with 1,2-diaminobenzene. Secondly, in methanol and DMF solvents, 1 showed two structures, the binuclear and mononuclear cobalt complexes 1 a and 1 b. Finally, the structure of 4 showed the formation of a new 2:1 type ligand at eutectic L2 in the presence of a Ni2+ template. Upon treatment with AIBN, 1-4 showed moderate to high activities for MMA polymerization, producing PMMA with low to high molecular weights (2.02 similar to 73.03 x10(4) g.mol(-1)) and moderate dispersity indices (PDI: 1.72 similar to 3.32). Moreover, 1 b displayed higher catalytic activities (up to 1.138x 10(5) g mol(-1) . h(-1)), which was 20 times higher than that of 3 and more than 7 times higher than that of 1 a.