Synthesis, structure, and catalytic activity of lanthanide Gd(III) and La(III) complexes with N-(cyclohexyl)isopropyl amidate ligand

AbstractTwo new lanthanide amidate complexes, {Gd2[Cy(NCO)iPr]6} (1) and {La2[Cy(NCO)iPr]6[Cy(HNCO)iPr]} (2) (iPr = isopropyl, Cy = cyclohexyl), have been synthesized in good yields by silylamine elimination reaction between Gd[N(SiMe3)2]3 or La[N(SiMe3)2]3 and N-(cyclohexyl)isopropyl amide. Complexes 1 and 2 have been characterized by NMR, elemental analyzes, and X-ray diffraction. The molecular structures of {[Cy(NCO)iPr]Gd[μ2-Cy(NCO)iPr]3Gd[Cy(NCO)iPr]2} (1) and {[Cy(NCO)iPr]La[μ2-Cy(NCO)iPr]3La[Cy(NCO)iPr]2[Cy(HNCO)iPr]} (2) exhibit a dimer structure with three μ2-O bridging bonds that look like a windmill. Additionally, 2 formed an intramolecular N–H···O hydrogen bond via a neutral amide. The catalytic properties of 1 and 2 for ring-opening polymerization (ROP) of ε-caprolactone have been studied. The results show that 1 and 2 are efficient catalysts for the ROP of ε-caprolactone.Keywords: Organolanthanide (Gd or La)N-(cyclohexyl)isopropyl amidePolymerization of ε-caprolactone AcknowledgmentsThis work was supported by National Science and Technology of Major Project (2009ZX02039-002), and Open Research Foundation of State Key Laboratory of ASIC & System (12KF007).