American Chemical Society
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Syntheses, Crystal Structures, and Properties of Six New Lanthanide(III) Transition Metal Tellurium(IV) Oxyhalides with Three Types of Structures

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journal contribution
posted on 2005-07-25, 00:00 authored by Yue-Ling Shen, Jiang-Gao Mao
Solid-state reactions of lanthanide(III) oxide (and lanthanide(III) oxyhalide), transition metal halide (and transition metal oxide), and TeO2 at high temperature lead to six new lanthanide transition metal tellurium(IV) oxyhalides with three different types of structures, namely, DyCuTe2O6Cl, ErCuTe2O6Cl, ErCuTe2O6Br, Sm2Mn(Te5O13)Cl2, Dy2Cu(Te5O13)Br2, and Nd4Cu(TeO3)5Cl3. Compounds DyCuTe2O6Cl, ErCuTe2O6Cl, and ErCuTe2O6Br are isostructural. The lanthanide(III) ion is eight-coordinated by eight oxygen atoms, and the copper(II) ion is five-coordinated by four oxygens and a halide anion in a distorted square pyramidal geometry. The interconnection of Ln(III) and Cu(II) ions by bridging tellurite anions results in a three-dimensional (3D) network with tunnels along the a-axis; the halide anion and the lone-pair electrons of the tellurium(IV) ions are oriented toward the cavities of the tunnels. Compounds Sm2Mn(Te5O13)Cl2 and Dy2Cu(Te5O13)Br2 are isostructural. The lanthanide(III) ions are eight-coordinated by eight oxygens, and the divalent transition metal ion is octahedrally coordinated by six oxygens. Two types of polymeric tellurium(IV) oxide anions are formed:  Te3O84- and Te4O104-. The interconnection of the lanthanide(III) and divalent transition metal ions by the above two types of polymeric tellurium(IV) oxide anions leads to a 3D network with long, narrow-shaped tunnels along the b-axis. The halide anions remain isolated and are located at the above tunnels. Nd4Cu(TeO3)5Cl3 features a different structure. All five of the Nd(III) ions are eight-coordinated (NdO8 for Nd(1), Nd(2), Nd(4), and Nd(5) and NdO7Cl for Nd(3)), and the copper(I) ion is tetrahedrally coordinated by four chloride anions. The interconnection of Nd(III) ions by bridging tellurite anions resulted in a 3D network with large tunnels along the b-axis. The CuCl4 tetrahedra are interconnected into a 1D two-unit repeating (zweier) chain via corner-sharing. These 1D copper(I) chloride chains are inserted into the tunnels of the neodymium(III) tellurite via Nd−Cl−Cu bridges. Luminescent studies show that ErCuTe2O6Cl and Nd4Cu(TeO3)5Cl3 exhibit strong luminescence in the near-IR region. Magnetic measurements indicate the antiferromagnetic interactions between magnetic centers in these compounds.