Dilithiated salen complexes: chiral [(salen)Li₂·hmpa]₂and deliberate partial hydrolysis to give [(salen)Li₂]₃·Li₂O·2tmen·H₂O [H₂salen =N,N′-ethylenebis(salicylideneimine); hmpa = hexamethylphosphoramide; tmen = tetramethylethylenediamine]

Abstract

Chiral [(salen)Li2·hmpa]2 has a Li4O4 cubane-type core in the solid but low-temperature NMR spectroscopy reveals a racemisation equilibrium in solution; deliberate addition of H2O to [(salen)Li2]n in the presence of tmen produces a species having two Li4O4 cubes sharing a common oxygen and containing tmen ligands acting in a hitherto unobserved monofunctional mode.