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The oxygen-bridged dinuclear rare earth complexes (Ln =Nd (1),Y (2)) bearing N-heterocyclic olefin moieties were synthesized by treating the imidazolidinium salt [SIMes-H]Br with potassium amide and rare earth bis(trimethylsilyl)amides.Complex 1 was characterized by X-ray diffraction analysis and complex 2 was characterized by 1H NMR spectroscopy.Both complexes were characterized by elemental analysis.Crystal data of complex 1:C74H138O2N8Si8Nd2,Mr =1685.12,orthorhombic,space group Pbca,a =25.1105(7),b =11.9188(2),c =29.6151 (7) (A),V =8863.4(4) (A)3,Z =4,Dc =1.263 g·cm-3,μ=1.311 mm-1,F(000) =3544,the final R =0.0418 and wR =0.0770 for all data.The ring-opening of tetrahydrofuran molecule was proven,the possible mechanism for the formation of N-heterocyclic olefin (NHO)-rare earth complexes was speculated and the electronic and steric properties of SIMes and rare earth amides were discussed.This work provides a better understanding of N-heterocyclic carbene rare earth chemistry.