Crystal structure of bis-[tetra-kis-(tetra-hydro-furan-κ)lithium] bis[μ-2,2',2''-methanetriyltris(4,6-di--butylphenolato)-κ,':','']-dimagnesiate.

The title ion-association metal complex, [Li(CHO)][Mg(CHO)], has been synthesized from the tridentate phenolic ligand tris-(3,5-di--butyl-2-hy-droxy-phen-yl)methane in tetra-hydro-furan (THF). The aryl-oxo magnesiate complex anion is binuclear with each MgO complex unit inversion-related and bridged through the two tridentate chelating phenolate O-donors of the ligand. The complex centres have a distorted tetra-hedral stereochemistry [Mg-O range 1.8796 (17)-2.0005 (16) Å] and an Mg⋯Mg separation of 2.9430 (14) Å]. The LiO coodination sphere of the cation comprises four THF O-donor atoms and has a slightly distorted tetra-hedral conformation [Li-O range 1.899 (5)- 1.953 (5) Å]. In the crystal, a number of stabilizing intra-anion C-H⋯O hydrogen-bonding inter-actions are present but no inter-species associations are found.