Two Cationic Copper(I) Catalysts with N-Donor Ligands for the Polymerization of Methyl Methacrylate

• Published in: Macromolecular chemistry and physics 2009-10, Vol.210 (19), p.1654-1660
• Main Authors: Liu, Guang-Fei, Li, Ling-Ling, Ren, Zhi-Gang, Li, Hong-Xi, Cheng, Zhen-Ping, Zhu, Jian, Zhu, Xiu-Lin, Lang, Jian-Ping
• Format: Article
• Language: English
• Subjects: Applied sciences; Catalysis; catalyst; Catalysts; Cationic; Conversion; copper(I) catalyst; crystal structure; Exact sciences and technology; Ligands; methyl methacrylate; Organic polymers; Physicochemistry of polymers; Polymerization; Polymethyl methacrylates; Preparation, kinetics, thermodynamics, mechanism and catalysts; Reaction time; synthesis
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.200900216

Two new copper(I) complexes, [Cu(bdmpm)2](PF6) (1) [bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane (bdmpm)] and [Cu(µ‐bdmpp)(MeCN)]2(PF6)2 (2) [2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridine (bdmpp)], were prepared by reactions of [Cu(MeCN)4](PF6) with bdmpm or bdmpp in MeCN. X‐ray analysis revealed that 1 is a mononuclear complex with the central Cu being chelated by two bdmpm ligands. 2 has a double‐stranded helicate structure in which each of the two [Cu(µ‐bdmpp)(MeCN)]+ cations is linked by the other bdmpp ligand. Both 1 and 2 exhibited high catalytic activity in the polymerization of methyl methacrylate (MMA). Even though the ratio of MMA to catalyst was raised up to 1 000:1, the PDI for 1 (reaction time was fixed at 5 h) is below 1.6 and the conversion is up to 66.0% while that for 2 (reaction time was fixed at 6 h) is below 1.5 and the conversion is up to 75.2%. In addition, the effects of solvents, reaction temperatures as well as ratios of MMA to catalyst were also investigated. Reaction of [Cu(MeCN)4](PF6) with bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane (bdmpm) or 2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridine (bdmpp) afforded two copper(I) complex [Cu(bdmpm)2](PF6) (1) and [Cu(‐bdmpp)(MeCN)]2(PF6)2 (2). Complex 1 has a mononuclear structure and 2 holds a double‐stranded helicate structure. The title complex showed high catalytic activity in the polymerization of methyl methacrylate (MMA). The polydispersity index (PDI) of the polymer is below 1.6 (for 1) and 1.5 (for 2) and the conversion yield is up to 66 (for 1) and 75.2 (for 2) when the ratio of MMA to catalyst was raised up to 1000:1 and the reaction time was fixed at 5 or 6h.