Synthesis of arene-soluble mixed-metal Zr/Ce, Zr/Y, and related [[Zr2(OiPr)9]LnX2]n complexes using the dizirconium nonaisopropoxide ligand

Heterometallic Group 4-Lanthanide Oxo-alkoxide Precursors for Synthesis of Binary Oxide Nanomaterials

In this study, an efficient procedure for the synthesis of uncommon group 4-lanthanide oxo-alkoxide derivatives was developed. Heterometallic clusters with the structures [La₂Ti₄(μ₄-O)₂(μ₃-OEt)₂(μ-OEt)₈(OEt)₆(Cl)₂(HOEt)₂] (1), [La₂Zr₂(μ₃-O)(μ-OEt)₅(μ-Cl)(OEt)₂(HOEt)₄(Cl)₄]_n (2), [La₂Hf₂(μ₃-O)(μ-OEt)₅(μ-Cl)(OEt)₂(HOEt)₄(Cl)₄]_n (3), [Nd₂Ti₄(μ₄-O)₂(μ₃-OEt)₂(μ-OEt)₈(OEt)₆(HOEt)₂(Cl)₂] (4), [Nd₄Zr₄(μ₃-O)₂(μ-OEt)₁₀(μ-Cl)₄(OEt)₈(HOEt)₁₀(Cl)₂] (5), and [Nd₄Hf₄(μ₃-O)₂(μ-OEt)₁₀(μ-Cl)₄(OEt)₈(HOEt)₁₀(Cl)₂] (6) were synthesized via the reaction of a metallocene dichloride, Cp₂M'Cl₂ (where M' = Ti, Zr, and Hf), and metallic lanthanum or neodymium in the presence of excess ethanol. This procedure gave crystalline precursors with molecular stoichiometries suitable for obtaining group 4-lanthanide oxide materials. Compounds 1-6 were examined by analytical and spectroscopic techniques and single-crystal X-ray diffraction. The magnetic properties of 5 and 6 were investigated by using direct and alternating current (dc and ac) susceptibility measurements. The results indicated weak antiferromagnetic interactions between Nd^III ions and a field-supported slow magnetic relaxation. Lanthanum-titanium compound 1 decomposed at 950 °C to give the perovskite compound La_0.66TiO₃ and small amounts of rutile TiO₂. Under the same conditions, 4 decomposed to give a mixture of Nd₄Ti₉O₂₄ and Nd_0.66TiO₃. When 4 was calcined at 1300 °C, decomposition of Nd₄Ti₉O₂₄ to Nd_0.66TiO₃ and TiO₂ was observed. Calcination of 2, 3, 5, and 6 at 950-1500 °C led to the selective formation of heterometallic La₂Zr₂O₇, La₂Hf₂O₇, Nd₂Zr₂O₇, and Nd₂Hf₂O₇ phases, respectively.

Post-Synthetic Shaping of Porosity and Crystal Structure of Ln-Bipy-MOFs by Thermal Treatment

The reaction of anhydrous lanthanide chlorides together with 4,4′-bipyridine yields the MOFs ∞2[Ln₂Cl₆(bipy)₃]·2bipy, with Ln = Pr − Yb, bipy = 4,4′-bipyridine, and ∞3[La₂Cl₆(bipy)₅]·4bipy. Post-synthetic thermal treatment in combination with different vacuum conditions was successfully used to shape the porosity of the MOFs. In addition to the MOFs microporosity, a tuneable mesoporosity can be implemented depending on the treatment conditions as a surface morphological modification. Furthermore, thermal treatment without vacuum results in several identifiable crystalline high-temperature phases. Instead of collapse of the frameworks upon heating, further aggregation under release of bipy is observed. ∞3[LaCl₃(bipy)] and ∞2[Ln₃Cl₉(bipy)₃], with Ln = La, Pr, Sm, and ∞1[Ho₂Cl₆(bipy)₂] were identified and characterized, which can also exhibit luminescence. Besides being released upon heating, the linker 4,4′-bipyridine can undergo activation of C-C bonding in ortho-position leading to the in-situ formation of 4,4′:2′,2′′:4′′,4′′′-quaterpyridine (qtpy). qtpy can thereby function as linker itself, as shown for the formation of the network ∞2[Gd₂Cl₆(qtpy)₂(bipy)₂]·bipy. Altogether, the manuscript elaborates the influence of thermal treatment beyond the usual activation procedures reported for MOFs.

Hydroxylaminato yttrate and samarate complexes

The first homoleptic anions of hydroxylaminato ate-complexes of yttrium and samarium of the formulae K[M(ON(i)Pr(2))(4)] (M = Y, Sm) have been prepared and structurally characterised featuring variations of the hapticity of their ON(i)Pr(2) ligands leading to different chain connectivities in their solid state aggregates.

Synthesis of arene-soluble mixed-metal uranium/zirconium complexes using the dizirconium nonaisopropoxide ligand

The utility of polydentate monoanionic [Zr(2)(O(i)Pr)(9)](-) (dzni) in generating arene-soluble, mixed-metal Zr/U complexes is described. K[Zr(2)(O(i)Pr)(9)] reacts readily with UI(3)(THF)(4) to form [Zr(2)(O(i)Pr)(9)]UI(2)(THF), 1, in >90% yield. The integrity of the [[Zr(2)(O(i)Pr)(9)]U](2+) unit in 1 was examined by the reaction of 1 with K(2)C(8)H(8), which formed the organometallic complex [Zr(2)(O(i)Pr)(9)]U(C(8)H(8)), 2. In contrast, the reaction of K[Zr(2)(O(i)Pr)(9)] with UCl(4) did not form U(IV)-dzni complexes, and only the ligand exchange product, [UCl(2)(O(i)Pr)(2)(DME)](2), 3, was isolated. The effect of the dzni ligand on the electrochemistry and near-infrared spectroscopy of U(III) is also described.