title: Calcium complexes containing oxalamidinate ligands as catalysts for ε-caprolactone polymerization.
abstract: A series of calcium complexes containing oxalamidinate ligands is described. Reactions of oxalamidinate ligand precursors, [PhN=C{NH(CH2)2OMe}-C{NH(CH2)2OMe}=NPh] (1), [PhN=C{NH(CH2)2NMe2}-C{NH(CH2)2NMe2}=NPh] (2), [Ph(TriMe)N=C{NH(CH2)2OMe}-C{NH(CH2)2OMe}=NPh(TriMe)] (3), [Ph(TriMe)N=C{NH(CH2)2SMe}-C{NH(CH2)2SMe}=NPh(TriMe)] (4), [Ph(TriMe)N=C{NHCH2Py}-C{NHCH2Py}=NPh(TriMe)] (5), with two molar equivalents of Ca[N(SiMe3)2]2(THF)2 gave calcium oxalamidinate complexes, [Ca{N(SiMe3)2}(THF)(PhN)C{N(CH2)2OMe}-]2 (6), [Ca{N(SiMe3)2}(THF)(PhN)C{N(CH2)2NMe2}-]2 (7), [Ca{N(SiMe3)2}(THF)(Ph(TriMe)N)C{N(CH2)2OMe}-]2 (8), [Ca{N(SiMe3)2}(THF)(Ph(TriMe)N)C{N(CH2)2SMe}-]2 (9), [Ca{N(SiMe3)2}(THF)(Ph(TriMe)N)C{NCH2Py}-]2 (10), respectively. The molecular structure of complex 7 was further characterized by the single crystal X-ray diffraction technique. The catalytic activities of complexes 6-10 toward the ring opening polymerization of ε-caprolactone were studied. Complex 8 exhibited excellent activity for the polymerization of ε-caprolactone with controlled molecular weights and polydispersities.
authors.affiliation: Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan.
authors.forename: Tzu-Lun
authors.initials: TL
authors.lastname: Huang
authors.forename: Chi-Tien
authors.initials: CT
authors.lastname: Chen
mesh_terms: D002118:Calcium / Q000737:chemistry*; D002208:Caproates / Q000737:chemistry*; D002384:Catalysis; D007783:Lactones / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D058105:Polymerization
chemical_list: D002208:Caproates; D007783:Lactones; D008024:Ligands; D009942:Organometallic Compounds; C121056:caprolactone; D002118:Calcium