Heterometallic 3d-4f Alkoxide Precursors for the Synthesis of Binary Oxide Nanomaterials

In this study, a new method for the synthesis of heterometallic 3d-4f alkoxides by the direct reaction of metallic lanthanides (La, Pr, Nd, Gd) with MCl₂ (M = Mn, Ni, Co) in 2-methoxyethanol was developed. The method was applied to the synthesis of the heterometallic oxo-alkoxide clusters [Ln₄Mn₂(μ₆-O)(μ₃-OR)₈(HOR)_xCl₆] (Ln = La (1), Nd (2), Gd (3); x = 0, 2, 4); [Pr₄M₂(μ₆-O)(μ₃-OR)₈(HOR)_xCl₆] (M = Co (4), Ni (5); x = 2, 4); and [Ln₄Mn₂(μ₃-OH)₂(μ₃-OR)₄(μ-OR)₄(μ-Cl)₂(HOR)₄Cl₆] (Ln = La (11) and Pr (12)). Mechanistic investigation led to the isolation of the homo- and heterometallic intermediates [Pr(μ-OR)(μ-Cl)(HOR)Cl]_n (6), [Co₄(μ₃-OR)₄(HOR)₄Cl₄] (7), [Ni₄(μ₃-OR)₄(HOEt)₄Cl₄] (8), [Mn₄(μ₃-OR)₄(HOR)₂(HOEt)₂Cl₄] (9), and [Nd(HOR)₄Cl][CoCl₄] (10). In the presence of an external M(II) source at 1100 °C, 1-4 and 12 were selectively converted into binary metal oxide nanomaterials with trigonal or orthorhombic perovskite structures, i.e., LaMnO₃, GdMnO₃, NdMnO₃, Pr_0.9MnO₃, and PrCoO₃. Compound 5 decomposed into a mixture of homo- and heterometallic oxides. The method presented provides a valuable platform for the preparation of advanced heterometallic oxide materials with promising magnetic, luminescence, and/or catalytic applications.

Syntheses, Structures, and Magnetic Properties of a Series of Heterotri-, Tetra- and Pentanuclear LnIII⁻CoII Compounds

Three types of Ln(III)⁻Co(II) heterometallic compounds, LnCo₂(L1)₇(bipy)₂ (Ln = Pr-1, Eu-2, Sm-3, Gd-4, Tb-5, Dy-6) (L1 = 4-chlorobenzoate, bipy = 2,2'-bipyridine), Ln₂Co₂(L₂)10(bipy)₂ (Ln = Sm-7, Gd-8, Tb-9, Dy-10, Ho-11, Er-12, Yb-13), (L2 = 2,4-dichlorobenzoate, bipy = 2,2'-bipyridine, phen = 1,10-phenanthroline), and Ln₂Co₃(L1)12(bipy)₂ (Ln = Ho-14, Er-15, Yb-16), were synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, IR spectroscopy and magnetic measurements. Structural analyses revealed that 14⁻16 take on a unique linear pentanuclear structural motif. Interestingly, the Ho-containing compound 14 exhibits magnetic relaxation behavior.

Influence of different metal ions on the assembly, structures, and properties of two complexes based on the semi-rigid bis(pyridyl)-bis(amide) ligand and 4,4′-oxybis(benzoic acid)

Two transitional metal complexes, [Zn(oba)(3-bpcd)] n (1) and [Cd(oba)(3-bpcd)0.5] n (2) [H2oba= 4,4′-oxybis(benzoic acid), 3-bpcd=N,N′-bis(pyridin-3-yl)cyclohexane-1,4-dicarboxamide], have been hydrothermally synthesized and structurally characterized by elemental analyses, infrared spectra, powder X-ray diffraction, thermogravimetric and single-crystal X-ray diffraction. Complex 1 possesses a three-fold interpenetrating network based on layers with a 4-connected sql topology. Complex 2 is a layered framework constructed by the oba anions and 3-bpcd ligands, which represents a binodal (3,4)-connected {62.10}{6} topology. The adjacent layers of complex 2 are further linked by hydrogen bonding interactions to build a three-dimensional supramolecular architecture. The differences of metal ions in coordination modes show a significant effect on the final structures of the Zn(II)/Cd(II) complexes. The photocatalytic activities and the fluorescence sensing properties of complexes 1 and 2 were investigated.