A series of calcium complexes containing oxalamidinate ligands is described. Reactions of oxalamidinate ligand precursors, [PhN![[double bond, length as m-dash]](http://www.rsc.org/images/entities/char_e001.gif)
C{NH(CH2)2OMe}–C{NH(CH2)2OMe}NPh] (1), [PhNC{NH(CH2)2NMe2}–C{NH(CH2)2NMe2}NPh] (2), [PhTriMeNC{NH(CH2)2OMe}–C{NH(CH2)2OMe}NPhTriMe] (3), [PhTriMeNC{NH(CH2)2SMe}–C{NH(CH2)2SMe}NPhTriMe] (4), [PhTriMeNC{NHCH2Py}–C{NHCH2Py}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.
Dalton Transactions
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