Calcium complexes containing oxalamidinate ligands as catalysts for ε-caprolactone polymerization
作者:Tzu-Lun Huang、Chi-Tien Chen
DOI:10.1039/c2dt32300a
日期:——
A series of calcium complexes containing oxalamidinate ligands is described. Reactions of oxalamidinate ligand precursors, [PhNCNH(CH2)2OMe}âCNH(CH2)2OMe}NPh] (1), [PhNCNH(CH2)2NMe2}âCNH(CH2)2NMe2}NPh] (2), [PhTriMeNCNH(CH2)2OMe}âCNH(CH2)2OMe}NPhTriMe] (3), [PhTriMeNCNH(CH2)2SMe}âCNH(CH2)2SMe}NPhTriMe] (4), [PhTriMeNCNHCH2Py}âCNHCH2Py}NPhTriMe] (5), with two molar equivalents of Ca[N(SiMe3)2]2(THF)2 gave calcium oxalamidinate complexes, [CaN(SiMe3)2}(THF)(PhN)CN(CH2)2OMe}â]2 (6), [CaN(SiMe3)2}(THF)(PhN)CN(CH2)2NMe2}â]2 (7), [CaN(SiMe3)2}(THF)(PhTriMeN)CN(CH2)2OMe}â]2 (8), [CaN(SiMe3)2}(THF)(PhTriMeN)CN(CH2)2SMe}â]2 (9), [CaN(SiMe3)2}(THF)(PhTriMeN)CNCH2Py}â]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 6â10 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.