New potentially tridentate amidinate ligand {o-MeOC6H4NC(Ph)N(SiMe3)}-. Synthesis and molecular structures of amidinate complexes of lithium [{o-MeOC6H4NC(Ph)N(SiMe3)}Li]2 and yttrium [{o-MeOC6H4NC(Ph)N(SiMe3)}YCl2(THF)2]2

The reaction of lithium silylamide ['o-MeOC6H4N(SiMe3)}Li(OEt2)](2) with 2 equiv. of benzonitrile in THF at similar to 20 A degrees C affords the lithium derivative of the new tridentate amidinate ligand [{o-MeOC6H4NC(Ph)N(SiMe3)}Li](2). The X-ray diffraction study showed that this complex has a dimeric structure due to the coordination of the N atoms and the ether group of one amidinate ligand to different Li atoms. The reaction of anhydrous YCl3 with the resulting complex in THF gives the monoamidinate complex [{o-MeOC6H4NC(Ph)N(SiMe3)}YCl2(THF)(2)](2) regardless of the reagent ratio. The latter has a dimeric structure in the crystalline state as a result of the presence of two mu(2)-bridging Cl atoms that link Y atoms. The ether groups of the amidinate ligands are not involved in the metal-ligand interaction.