title: Dinuclear magnesium, zinc and aluminum complexes supported by bis(iminopyrrolide) ligands: synthesis, structures, and catalysis toward the ring-opening polymerization of ε-caprolactone and rac-lactide.
abstract: Synthesis and characterization of novel dinuclear magnesium, zinc and aluminum complexes supported by bis(iminopyrrolide) ligands and their catalysis toward the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) and rac-lactide (rac-LA) were carried out. The ligand precursors [(5-Bu(t)-2-C4H2NH)CH=N(CH2)2]2NH (H2L(Bu), 1) and [(2-C4H3NH)CH=N(CH2)2]2NH (H2L(H), 2) were prepared by condensation of diethylene triamine with 5-tert-butyl-1H-pyrrole-2-carbaldehyde and 1H-pyrrole-2-carbaldehyde, respectively. Treatment of 1 with 2 equiv. of Bu(n)MgOBn in toluene at 70 °C produced dinuclear magnesium complex [(μ-OBn)2Mg2L(Bu)] (3). Similar treatment of 1 with EtZnOBn generated [(μ-OBn)2Zn2L(Bu)] (4). Reaction of 2 with 2 equiv. of Me2AlOBn in toluene at 70 °C afforded aluminum complex [Me2Al(μ-OBn)2AlL(H)] (5). Complexes 3-5 were characterized by (1)H and (13)C NMR spectroscopy, elemental analyses, and single crystal X-ray diffraction techniques. Each of complexes 3-5 is active for the ROP of ε-CL and rac-LA. Kinetic studies of the polymerization reactions were performed.
authors.affiliation: CAS Key Laboratory of Soft Matter Chemistry and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China. zxwang@ustc.edu.cn.
authors.forename: Wei-Li
authors.initials: WL
authors.lastname: Kong
authors.forename: Zhong-Xia
authors.initials: ZX
authors.lastname: Wang
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D000588:Amines / Q000737:chemistry; D002208:Caproates / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D004146:Dioxanes / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D008024:Ligands; D008274:Magnesium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D058105:Polymerization; D011108:Polymers / Q000737:chemistry; D011336:Probability; D012997:Solvents; D013696:Temperature; D014050:Toluene / Q000737:chemistry; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry*
chemical_list: D000588:Amines; D002208:Caproates; D004146:Dioxanes; D007783:Lactones; D008024:Ligands; D011108:Polymers; D012997:Solvents; D014050:Toluene; C121056:caprolactone; C091880:dilactide; D000535:Aluminum; D008274:Magnesium; D015032:Zinc