Synthesis, structure, and reactivity of polymetallic sodium and lanthanum 4-methylphenoxide complexes

Abstract

LaCl[sub 3] reacts with 4.5 equiv of sodium 4-methylphenoxide, 1, in THF to form La[sub 2]Na[sub 3]([mu][sub 4]-OR)[sub 3]([mu]-OR)[sub 6](THF)[sub 5], 2, in 80% yield (R = C[sub 6]H[sub 4]Me-4). Compound 2 crystallizes from toluene in the orthorhombic space group Pcca with a = 18.159(6) [angstrom], b = 18.474(17) [angstrom], c = 25.145(18) [angstrom], V = 8435(9) [angstrom][sup 3], and D[sub calcd] = 1.32 g cm[sup [minus]3] for Z = 8. The five metal atoms in this complex define a trigonal bipyramid with lanthanum in the axial positions and sodium in the equatorial positions. Bridging aryloxide ligands are located at each of the nine edges of the trigonal bipyramid and each metal is ligated by a terminal THF. When 2 is crystallized from THF/benzene/dioxane, a dioxane-solvated complex is formed in 88% yield: ([La[sub 2]Na[sub 3]([mu][sub 4]-OR)[sub 3]([mu]-OR)[sub 6]][([mu]-dioxane)[sub 2](dioxane)[sub 3]](dioxane))n, 3. Compound 3 crystallized in the monoclinic space group P2[sub 1]/c with a = 18.854(3)[angstrom], b = 16.624(2) [angstrom], c = 29.561(5) [angstrom], [beta] = 108.36(1)[degrees], V = 8793(2) [angstrom][sup 3], and D[sub calcd] = 1.39 g cm[sup [minus]3] for Z = 4. Least-squares refinement on the basis of 8127 observed reflections led to a final R[sub F] = 4.9%.more » The connectivity of the metals and aryloxide ligands in 2 is retained in 3. However, dioxane molecules replace the THF in 2 and link the trigonal bipyramids together through Na-([mu]-dioxane)-La bridges.« less