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Issue 25, 2013
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Calcium complexes containing oxalamidinate ligands as catalysts for ε-caprolactone polymerization

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Abstract

A series of calcium complexes containing oxalamidinate ligands is described. Reactions of oxalamidinate ligand precursors, [PhN[double bond, length as m-dash]C{NH(CH2)2OMe}–C{NH(CH2)2OMe}[double bond, length as m-dash]NPh] (1), [PhN[double bond, length as m-dash]C{NH(CH2)2NMe2}–C{NH(CH2)2NMe2}[double bond, length as m-dash]NPh] (2), [PhTriMeN[double bond, length as m-dash]C{NH(CH2)2OMe}–C{NH(CH2)2OMe}[double bond, length as m-dash]NPhTriMe] (3), [PhTriMeN[double bond, length as m-dash]C{NH(CH2)2SMe}–C{NH(CH2)2SMe}[double bond, length as m-dash]NPhTriMe] (4), [PhTriMeN[double bond, length as m-dash]C{NHCH2Py}–C{NHCH2Py}[double bond, length as m-dash]NPhTriMe] (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)(PhTriMeN)C{N(CH2)2OMe}–]2 (8), [Ca{N(SiMe3)2}(THF)(PhTriMeN)C{N(CH2)2SMe}–]2 (9), [Ca{N(SiMe3)2}(THF)(PhTriMeN)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.

Graphical abstract: Calcium complexes containing oxalamidinate ligands as catalysts for ε-caprolactone polymerization

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Publication details

The article was received on 01 Oct 2012, accepted on 06 Nov 2012 and first published on 06 Nov 2012


Article type: Paper
DOI: 10.1039/C2DT32300A
Citation: Dalton Trans., 2013,42, 9255-9262
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    Calcium complexes containing oxalamidinate ligands as catalysts for ε-caprolactone polymerization

    T. Huang and C. Chen, Dalton Trans., 2013, 42, 9255
    DOI: 10.1039/C2DT32300A

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