LANTHANOID COMPLEXES .9. REACTIVITY CONTR OL OF LANTHANOID AMIDES THROUGH LIGAND EFFECTS - SYNTHESIS AND STRUCTURES OF STERICALLY CONGESTEDALKOXY COMPLEXES

It is shown that the introduction of sterically demanding ligands in l anthanoid metal complexes can depend more on the precise composition o f the lanthanoid precursor than on the size of the new ligand. Thus, t ris(t-butyl)methanol (''tritox-H'') does not react with the amides Ln[ N(SiMe(3))(2)](3) of the ''late'' (small) lanthanoid metals. However, fast and clean reactions occur with the sterically less demanding deri vatives Ln[N(SiHMe(2))(2)](3), with new homoleptic complexes Ln(tritox )(3) (Ln = Y, Nd) being formed with practically all metals of this gro up of elements. The molecular and crystal structures of some lanthanoi d amides and alkoxides are described.