[(bmppy)Cu(μ-I)]2 (bmppy = 2,6-bis(1-methyl-1H-pyrazol-3-yl)pyridine): Synthesis, crystal structure and its catalytic performance for MMA polymerization

•Reaction of CuI with bmppy afforded one binuclear complex [(bmppy)Cu(μ-I)]2.•Complex 1 exhibited high catalytic activity for the polymerization of MMA.•Solvent, temperature and catalyst loadings affect the catalytic activities of 1.

Reaction of CuI with equimolar amount of 2,6-bis(1-methyl-1H-pyrazol-3-yl)pyridine (bmppy) in MeCN and CH2Cl2 yielded a binuclear complex [(bmppy)Cu(μ-I)]2 (1). It was characterized by elemental analysis, IR, 1H NMR and single crystal X-ray diffraction. Complex 1 possesses an iodide-bridged dimeric structure in which each Cu(I) center is tetrahedrally coordinated by two μ-I and two N atoms from one bmppy ligand. Complex 1 exhibited good catalytic performance in the polymerization of methyl methacrylate (MMA) in cyclohexanone. Even though the ratio of MMA to 1 was raised up to 1000:1 when the reaction time and temperature and the MMA concentration were fixed at 4 h and 80 °C and 3 mol/L, respectively, the polydispersity index (PDI) for the resulting PMMA is close to 1.36 and the conversion is up to 75%. In addition, the effects of solvents, reaction temperatures as well as the ratios of MMA to catalyst 1 were also investigated.

Graphical abstractTreatment of CuI with equimolar bmppy in MeCN and CH2Cl2 afforded [(bmppy)Cu(μ-I)]2. This complex has an iodide-bridged dimeric structure, and could efficiently initiate the polymerization of MMA in cyclohexanone at 80 °C to produce relatively high molecular weight polymers with narrow molecular weight distributions (PDI = 1.23) in good yields.Figure optionsDownload full-size imageDownload as PowerPoint slide