Lanthanide(III) Di- and Tetra-Nuclear Complexes Supported by a Chelating Tripodal Tris(Amidate) Ligand

Syntheses, structural, and spectroscopic characterization of multinuclear tris­(amidate) lanthanide complexes is described. Addition of K₃[N­(<i>o</i>-PhNC­(O)<i>^t</i>Bu)₃] to LnX₃ (LnX₃ = LaBr₃, CeI₃, and NdCl₃) in <i>N</i>,<i>N</i>-dimethylformamide (DMF) results in the generation of dinuclear complexes, [Ln­(N­(<i>o</i>-PhNC­(O)^<i>t</i>Bu)₃)­(DMF)]₂­(μ-DMF) (Ln = La (<b>1</b>), Ce (<b>2</b>), Nd­(<b>3</b>)), in good yields. Syntheses of tetranuclear complexes, [Ln­(N­(<i>o</i>-PhNC­(O)^<i>t</i>Bu)₃)]₄ (Ln = Ce (<b>4</b>), Nd­(<b>5</b>)), resulted from protonolysis of Ln­[N­(SiMe₃)₂]₃ (Ln = Ce, Nd) with N­(<i>o</i>-PhNCH­(O)^<i>t</i>Bu)₃. In the solid-state, complexes <b>1</b>–<b>5</b> exhibit coordination modes of the tripodal tris­(amidate) ligand that are unique to the 4f elements and have not been previously observed in transition metal systems