Synthesis of homoleptic lanthanide amides and the crystal structure of [Li(THF)4][Y(NPh2)4]

Anhydrous LnCl₃ reacted with three equivalents of LiNPh₂ in THF to give the unexpected homoleptic lanthanide amides Li(THF)₄]Ln(NPh₂)₄] (Ln = Sm (1), Y (2)) in high yield. The crystal structure of complex 2 has been determined by X-ray diffraction methods. It crystallizes in the orthorhombic space group Pbcn with a = 17.522(3) Å, b = 16.321(3) Å, c = 19.947(3) Å, V = 5704.4(17) ų, and D _calc = 1.231 mg/m³ for Z = 4. Complex 2 is composed of discrete Li(THF)₄]⁺ cations and Y(NPh₂)₄]^– anions, both of which have crystallographically imposed two-fold symmetry. To achieve steric saturation of the metal center, there are interactions between the yttrium atom and one -carbon atom of each amide ligand. The yttrium and lithium atoms both exhibit distorted tetrahedral coordination geometry.