The First Trimetallic Lithium-Sodium-Potassium Complex: Synthesis and Crystal Structure of a Twelve-Vertex Li_2Na_2K_2N_4O_2 Cage Molecule Containing an Amide-Alkoxide Combination

摘要

Several molecular complexes containing a mixture of two alkali metals (e.g., lithium—sodium and lithium—potassium) have been characterised by X-ray crystallographic studies over the past decade. Here, in this paper, we break new ground in this important area of intermetallic chemistry by reporting the successful synthesis and X-ray crystallographic characterization of an unprecedented bimetallic (lithium-sodium-potassium) formulation. Furthermore, the new complex, [{[PhN(H)]_2(t-BuO)LiNaK centre dot (TMEDA)_2}_2], (1), is closely related to the co-compositions currently employed as "superbases", reagents of boosted deprotonating ability, in organic synthesis. Two recently reported crystal structures regarded to be architectural models for superbases, a carbaniori-alkoxide and a carbanion—amide combination, both contain their two anionic functionalities (CT/RCT and C~-/R_2N~-, respectively) within one ligand. On the other hand, more realistically, 1 contains two distinct types of anionic ligand [amide—alkoxide (R_2N~-/RO~-)]~4 as is the case in superbase reagents.