Synthesis and Structural Characterization of a Series of Lanthanide(II) Amides:Steric Effect of Amido Ligand

摘要

The synthesis and structures of a series of lanthanide(II) and lanthanide(III) complexes supported by the amido ligand N(SiMe3)Ar were described.Several lanthanide(III) amide chlorides were synthesized by a metathesis reaction of LnCl3 with lithium amide,including {[(C6H5)(Me3Si)N]2YbCI(THF)}2-PhCH3 (1),[(C6H3-~iPr2-2,6)(SiMe3)N]2YbCI-(mu-Cl)Li(THF)3 centre dot PhCH3 (4),[(C6H3-~iPr2-2,6)(SiMe3)N]YbCI2(THF)3 (6),and [(C6H3-~iPr2-2,6)(SiMe3)N]2SmCI3Li2(THF)4 (7).The reduction reaction of 1 with Na-K alloy afforded bisamide ytterbium(II) complex [C6H5)(Me3Si)N]2Yb-(DME)2 (2).The same reaction for Sm gave an insoluble black powder.An analogous samarium(ll) complex [(C6H5)(Me3Si)N]2Sm(DME)2 (3) was prepared by the metathesis reaction of Sml2 with NaN(C6H5)(SiMe3).The reduction reaction of ytterbium chloride 4 with Na-K alloy afforded monoamide chloride {[(C6H3-~iPr2-2,6)(SiMe3)N]-Yb(mu-CI)(THF)2}2 (5),which is the first example of ytterbium(II) amide chloride,formed via the cleavage of the Yb-N bond.The same reduction reaction of 7 gave a normal bisamide complex [(C6H3-~iPr2-2,6)(SiMe3)N]2Sm-(THF)2 (8) via Sm-CI bond cleavage.This is the first example for the steric effect on the outcome of the reduction reaction in lanthanide(II) chemistry.5 can also be synthesized by the Na/K alloy reduction reaction of 6.All of the complexes were fully characterized including X-ray diffraction for 1-7.