Synthetic and structural investigations of alkali metal diamine bis(phenolate) complexes

Two lithium and one sodium diamine bis(phenolate) complexes have been prepared and characterised by X-ray crystallography and NMR spectroscopy. Two parent diamine bis(phenol) ligands were utilised in the study (1-H2 and 2-H2). Dimeric (1-Li2)2 was prepared by treating 1-H2 with two molar equivalents of n-butyllithium in hydrocarbon solvent. It adopts a ladder-like structure in the solid state, which appears to deaggregate in C6D6 solution. The monomeric (hence, dinuclear) TMEDA-solvated species [2-Li2·(TMEDA)] has two chemically unique Li atoms in the solid state and is prepared by reacting 2-H2 with two molar equivalents of n-butyllithium in hydrocarbon solvent, in the presence of N,N,N′,N′-tetramethylethylenediamine (TMEDA). Finally, the dimeric sodium-based [2-Na2·(OEt2)]2 was prepared by reacting 2-H2 with two molar equivalents of freshly prepared n-butylsodium in a hydrocarbon–diethyl ether medium. The complex adopts a Na4O4 cuboidal structure in the solid state, which appears to remain intact in C6D6 solution.