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

Abstract

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.