[Lithium Piperidide–Piperidine]4: Crystal Structure of an Oligomeric 1:1 Lithium Amide–Amine Mixed Complex, an Intermediate in the N‐Lithiation of Amines

A model for the mechanism of formation of ladder structures for lithium amides is provided by the title compound 1, the first oligomeric mixed complex of a lithium amide with an amine (structure depicted to the right, where one piperidine ligand has been omitted from each of Li1 and Li2). The structure in the solid state is in accord with results of calculations on similar 1:1 complexes as well as with 13C NMR studies in solution. Reactions of lithium piperidide with CO in the presence of piperidine also suggest that such complexes are reactive intermediates.