Crystal structure of bis(mu(2)-methoxy-kappa O:kappa O)hexamethylbis(mu(2)-triphenylacetato-kappa O:kappa O ')bis(mu(2)-triphenylacetato-kappa O-2,O ':kappa O)dialuminium-dilanthanum toluene tetrasolvate

The title compound, [Al2La2(C20H15O2)(4)(CH3)(6)(CH3O)(2)]center dot 4CH(3)C(6)H(5) or [{La(Ph3CCOO)(2)(Me3AlOMe)}(2)]center dot 4CH(3)C(6)H(5), was formed in a reaction between lanthanum tris(tetramethylaluminate) and triphenylacetic acid (1:1) with unintended partial oxidation. The triphenylacetate ligand exhibits mu(2)-kappa O-1:kappa O-1' bridging and mu(2)-kappa O-2,O':kappa O-1 semi-bridging coordination modes, forming a dimeric La-2(mu-OCO)(4) core. The semi-bridging triphenylacetate group provides additional bonding with an La3+ cation via the pi-system of one of its phenyl rings. The trimethylmethoxyaluminate anion, which is coordinated to the La3+ cation by its O atom, displays a rather long La-C-Me bond. Two toluene molecules 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 pi-bounded arene fragments.