Crystal structure of bis-(μ2-meth-anolato-κ O:κ O)hexa-methyl-bis-(μ2-tri-phenyl-acetato-κ O:κ O')bis-(μ2-tri-phenyl-acetato-κ2 O, O':κ O)dialuminiumdi-lanthanum toluene tetra-solvate

Abstract

The title compound, [Al₂La₂(C₂₀H₁₅O₂)₄(CH₃)₆(CH₃O)₂]·4CH₃C₆H₅ or [{La(Ph₃CCOO)₂(Me₃AlOMe)}₂]·4CH₃C₆H₅, 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 μ₂-κ¹ O:κ¹ O' bridging and μ₂-κ² O,O':κ¹ O semi-bridging coordination modes, forming a dimeric La₂(μ-OCO)₄ core. The semi-bridging tri-phenyl-acetate group provides additional bonding with an La³⁺ cation via the π-system of one of its phenyl rings. The tri-methyl-meth-oxy-aluminate anion, which is coordinated to the La³⁺ 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.

Keywords: aluminium; coordination compound; crystal structure; lanthanum; tri­phenyl­acetate; π-complex.