Crystal structure of bis-(μ 2 -meth-anolato-κ O :κ O )hexa-methyl-bis-(μ 2 -tri-phenyl-acetato-κ O :κ O ')bis-(μ 2 -tri-phenyl-acetato-κ 2 O , O ':κ O )dialuminiumdi-lanthanum toluene tetra-solvate.

The title compound, [Al ₂ La ₂ (C ₂₀ H ₁₅ O ₂ ) ₄ (CH ₃ ) ₆ (CH ₃ O) ₂ ]·4CH ₃ C ₆ H ₅ or [{La(Ph ₃ CCOO) ₂ (Me ₃ AlOMe)} ₂ ]·4CH ₃ C ₆ H ₅ , was formed in a reaction between lanthanum tris-(tetra-methyl-aluminate) and tri-phenyl-acetic acid (1:1) with unintended partial oxidation. The tri-phenyl-acetate ligand exhibits μ ₂ -κ ¹ O :κ ¹ O ' bridging and μ ₂ -κ ² O , O ':κ ¹ O semi-bridging coordination modes, forming a dimeric La ₂ (μ-OCO) ₄ core. The semi-bridging tri-phenyl-acetate group provides additional bonding with an La ³⁺ cation via the π-system of one of its phenyl rings. The tri-methyl-meth-oxy-aluminate anion, which is coordinated to the La ³⁺ cation by its O atom, displays a rather long La-C _Me bond. Two toluene mol-ecules are each disordered over two orientations about centres of symmetry with site occupancy factors of 0.5. The title compound represents the first example of an Ln ^III complex containing both alkyl alkoxide aluminate and π-bounded arene fragments.