Isolation and structural characterization of the first homoleptic lanthanide–zirconium oxoisopropoxide, La2Zr3O(OPri)16. Combination of an [M4O] tetrahedron with an [MO6] octahedron – A new structure type for pentanuclear alkoxide complexes

The amorphous bimetallic isopropoxides of variable composition LaZrnOx(OPri)3+4n−2x, where n = 0.5–3 formed on interaction of the two homometallic isopropoxides, La5O(OiPr)13 and Zr(OiPr)4(iPrOH), in solutions in parent alcohol crystallize slowly yielding a bimetallic oxoalkoxide La2Zr3O(OPri)16 (1). In its molecule an octahedrally coordinated zirconium atom is connected via two μ3-OR and two μ-OR-groups with two lanthanum atoms of a tetrahedral [La2Zr2(μ4-O)] aggregate. This structure type has not been previously observed in the structures of pentanuclear alkoxide aggregates. The conditions leading to formation of 1 from solutions containing the homometallic alkoxides are outlined.