Rich Structural Chemistry in Scandium Selenium/Tellurium Oxides: Mixed-Valent Selenite–Selenates, Sc2(SeO3)2(SeO4) and Sc2(TeO3)(SeO3)(SeO4), and Ternary Tellurite, Sc2(TeO3)3

Two Purely Inorganic Cationic Tellurite Materials Based on Group IB Metal Tetrafluoroborates with Similar Lamellar Cationic Layers: [Cu2F(Te2O5)](BF4) and [Ag18O2(Te4O9)4(Te3O8)(BF4)2]·2HBF4

Two new purely inorganic cationic tellurite networks of Group IB metal-based tetrafluoroborates, namely, [Cu₂F(Te₂O₅)](BF₄), 1, and [Ag₁₈O₂(Te₄O₉)₄(Te₃O₈)(BF₄)₂]·2HBF₄, 2, have been hydrothermally synthesized under mild conditions. The prepared materials have been characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR and Raman spectroscopy, SEM-energy-dispersive spectroscopy, UV-vis-NIR diffuse reflectance, magnetic study, and TG analyses. Single-crystal diffraction studies show that both materials have similar cationic Cu/Ag tellurite layers with tetrafluoroborates as interlamellar charge-balancing anions. Magnetic results indicate that [Cu₂F(Te₂O₅)](BF₄), 1, exhibits a mainly short-range antiferromagnetic ordering within the 2D layer, and further detailed analysis of magnetic susceptibility analysis confirms a spin-singlet ground state with an energy gap of 85 K.

Synthesis and crystal structure of two scandium oxotellurates(IV): Sc2Te3O9 and Sc2Te4O11

The two new scandium oxotellurates(IV) Sc2Te3O9 and Sc2Te4O11 were synthesized through firing appropriate mixtures of Sc2O3, TeO2 and CsBr (as flux) in evacuated glassy silica ampoules at 850 °C for 10 days. Both of them crystallize in the monoclinic space group P21/c with Z = 4 (Sc2Te3O9: a = 523.36(3), b = 2438.23(14), c = 731.98(4) pm, β = 116.221(3)°; Sc2Te4O11: a = 949.51(6), b = 779.12(5), c = 1341.93(9) pm, β = 90.829(3)°). Both crystal structures contain two crystallographically unique Sc3+ cations. In the case of Sc2Te3O9, they reside in six- and sevenfold oxygen coordination arranged as distorted uncapped or capped octahedra, while for Sc2Te4O11, they only exhibit six oxygen atoms in the coordination polyhedra, but one of them has also a certain tendency to thrive for a higher coordination number (C.N. = 6 + 1). The [(Sc1)O6)]9− and [(Sc2)O6+1)]11− polyhedra in Sc2Te3O9 are condensed via common edges to form serrated   ∞ 1 { [ Sc 2 O 6 / 1 t O 1 / 2 v O 4 / 2 e ] 11 − } ${\text{ }}_{\infty }^{1}\left\{{\left[{\text{Sc}}_{2}{\text{O}}_{6\text{/}1}^{\text{t}}{\text{O}}_{1\text{/}2}^{\text{v}}{\text{O}}_{4\text{/}2}^{\text{e}}\right]}^{11-}\right\}$ chains running along [100], whereas the two [ScO6]9− octahedra in Sc2Te4O11 only share common vertices, generating   ∞ 1 { [ Sc 2 O 6 / 1 t O 3 / 2 v ] 9 − } ${\text{ }}_{\infty }^{1}\left\{{\left[{\text{Sc}}_{2}{\text{O}}_{6\text{/}1}^{\text{t}}{\text{O}}_{3\text{/}2}^{\text{v}}\right]}^{9-}\right\}$ double strands along [010]. In both compounds, the three-dimensional framework and the charge balance are accomplished by the discrete ψ1-tetrahedral [TeO3]2− anions with non-bonding lone-pair electrons located at their central Te4+ cations. Moreover, strong secondary Te4+···O2− interactions, which are generally quite common for rare earth metal(III) oxotellurates(IV), occur in both crystal structures, but much more pronounced in Sc2Te4O11, where three quarters of the Te4+ cations reside in the centers of ψ eq 1 ${{\psi}}_{\text{eq}}^{1}$ -trigonal bipyramids [TeO4]4− as compared to Sc2Te3O9, which can well be written as Sc2[TeO3]3.

Zn(H2C3N3O3)2·3H2O: the first single-d10 transition metal based ultraviolet hydroisocyanurate crystal with large birefringence

The first single-d¹⁰ transition metal hydroisocyanurate crystal was designed and synthesized successfully with large band gaps and optical anisotropy.

In situ hydrothermal synthesis of polar second-order nonlinear optical selenate Na5(SeO4)(HSeO4)3(H2O)2

An alkali–metal selenate nonlinear optical (NLO) crystal, Na₅(SeO₄)(HSeO₄)₃(H₂O)₂, which possesses good second-order nonlinear optical properties, has been obtained by mild in situ hydrothermal synthesis.

The complete series of sodium rare-earth metal(III) chloride oxotellurates(IV) Na2 RE 3Cl3[TeO3]4 (RE = Y, La–Nd, Sm–Lu)

The complete series of sodium rare-earth metal(III) chloride oxotellurates(IV) with the composition Na2 RE 3Cl3[TeO3]4 (RE = Y, La–Nd, Sm–Lu) has been synthesized via solid-state reactions. For these conversions mixtures of the respective rare-earth metal(III) oxides, tellurium dioxide and sodium chloride as flux and reactant were prepared, intimately ground and heated for 5 days at 1225 K. The almost colorless single crystals were characterized via single-crystal X-ray diffractometry. In the monoclinic crystal structure of these compounds two crystallographically different rare-earth metal(III), but only one sodium cation sites occur. [REO8]13− polyhedra around both RE 3+ positions as well as sodium-centered polyhedra [NaO4Cl4]8− form layers via different connectivity modes. These layers spread out parallel to the (001) plane and arrange alternatingly resulting in the three-dimensional network of the Na2 RE 3Cl3[TeO3]4 structure, where the Te4+ lone-pair cations at two different sites work as linkers by forming isolated ψ 1-tetrahedra [TeO3]2−. Some of these compounds were represented before in different settings of space group C2/c. Now the complete series of the Na2 RE 3Cl3[TeO3]4 representatives with RE = Y, La–Nd, Sm–Lu is described consistently for a better comparison and understanding. Additionally, a single crystal of Na2Pr3Cl3[TeO3]4 was measured via energy dispersive X-ray analysis to verify the included elements, powder samples of Na2Nd3Cl3[TeO3]4 were characterized by X-ray diffractometer data for a phase-purity check and a single-crystal Raman spectrum of Na2Yb3Cl3[TeO3]4 served for proving the signature of discrete [TeO3]2− anions.

Exploration of New Birefringent Crystals in Bismuth d0 Transition Metal Selenites

The first examples of bismuth fluoride selenites with d⁰ -TM/Te^VI polyhedrons, namely, Bi₄ TiO₂ F₄ (SeO₃ )₄ (1), Bi₄ NbO₃ F₃ (SeO₃ )₄ (2), Bi₄ TeO₄ F₂ (TeO₃ )₂ (SeO₃ )₂ (3), Bi₂ F₂ (MoO₄ )(SeO₃ ) (4) and Bi₂ ZrO₂ F₂ (SeO₃ )₂ (5) have been successfully synthesized under hydrothermal reactions by aliovalent substitution. The five new compounds feature three different types of structures. Compounds 1-3, containing Ti^IV , Nb^V and Te^VI respectively, are isostructural, exhibiting a new 3D framework composed of a 3D bismuth oxyfluoride architecture, with intersecting tunnels occupied by d⁰ -TM/Te^VI octahedrons and selenite/tellurite groups. Interestingly, compound Bi₄ TeO₄ F₂ (TeO₃ )₂ (SeO₃ )₂ (3) is the first structure containing Se^IV and mixed-valent Te^IV /Te^VI cations simultaneously. Compound 4 features a new 3D structure formed by a 3D bismuth oxyfluoride network with MoO₄ tetrahedrons and selenites groups imbedded in the 1D tunnels. Compound 5 displays a novel pillar-layered 3D open framework, consisting of 2D bismuth oxide layers bridged by the [ZrO₂ F₂ (SeO₃ )₂ ]^6- polyanions. Theoretical calculations revealed that the five compounds displayed very strong birefringence. The birefringence values of compounds 1-3, especially, are above 0.19 at 1064 nm, which are larger than the mineral calcite. Based on the structure and property analysis, it was found that the asymmetric SeO₃ groups (and TeO₃ in compound 3) displayed the largest anisotropy, compared with the bismuth cations and the d⁰ -TM/Te polyhedra, which is beneficial to the birefringence.

Structural modulation induced by MIIIA metals in Ba3MQ4X (M = Al, Ga, In; Q = S, Se; X = Cl, Br): an experimental and computational analysis

The optical properties of Ba₃MQ₄X (M = Al, Ga, In; Q = S, Se; X = Cl, Br) have been studied and their structures have been compared.

Synthesis and structural variety of first Mn and Bi selenites and selenite chlorides

Single crystals of new Mn2[Bi2O](SeO3)4 (I), MnBi(SeO3)2Cl (II), MnIIMnIII(SeO3)2Cl (III), Mn5(SeO3)2Cl6 (IV), and Mn4(Mn5,Bi)(SeO3)8Cl5 (V) have been synthesized by chemical vapour transport and hydrothermal methods. They have been structurally characterized by single crystal X-ray diffraction analysis. The compounds II–V are the first Mn selenite chlorides, while the I, II and V compounds are the first Bi-containing Mn oxoselenites. Structural relationships of the new phases with other compounds are discussed. An overview of the mixed-ligand MnO m Cl n polyhedra in inorganic compounds is given.

Li3Ge3Se6: the first ternary lithium germanium selenide with interesting∞[Ge6Se12]nchains constructed by ethane-like [Ge2Se6]6−clusters

The first lithium germanium selenide, Li₃Ge₃Se₆with the first discovered chain formed by [Ge₂Se₆]⁶⁻clusters in the [Li₃Se₆] tunnels.

Na2CdGe2Q6(Q = S, Se): two metal-mixed chalcogenides with phase-matching abilities and large second-harmonic generation responses

Two metal-mixed chalcogenides with phase-matching abilities and large SHG responseshave been systematically reported.

Toward the Rational Design of Novel Noncentrosymmetric Materials: Factors Influencing the Framework Structures

Solid-state materials with extended structures have revealed many interesting structure-related characteristics. Among many, materials crystallizing in noncentrosymmetric (NCS) space groups have attracted massive attention attributable to a variety of superb functional properties such as ferroelectricity, pyroelectricity, piezoelectricity, and nonlinear optical (NLO) properties. In fact, the characteristics are pivotal to many industrial applications such as laser systems, optical communications, photolithography, energy harvesting, detectors, and memories. Thus, for the past several decades, a great deal of synthetic effort has been vigorously made to realize these technologically important properties by improving the occurrence of macroscopic NCS space groups. A bright approach to increase the incidence of NCS structures was combining local asymmetric units during the initial synthesis process. Although a significant improvement has been achieved in obtaining new NCS materials using this strategy, the majority of solid-state materials still crystallize in centrosymmetric (CS) structures as the locally unsymmetrical units are easily lined up in an antiparallel manner. Therefore, discovering an effective method to control the framework structure and the macroscopic symmetry is an imminent ongoing challenge. In order to more effectively control the overall symmetry of solid-state compounds, it is critical to understand how the backbone and the subsequent centricity are affected during the crystallization. In this Account, several factors influencing the framework structure and centricity of solid-state materials are described in order to more systematically discover novel NCS materials. Recent studies on crystalline solid-state materials suggest three factors affecting the local coordination environment as well as the overall symmetry of the framework structure: (1) size variations of the various template cations, (2) a variable backbone arrangement occurring from the hydrogen-bonding interactions, and (3) the presence of framework flexibility. With regard to the first factor, the impact of size of the various metal cations and coordination numbers on the alignment of other adjacent polyhedra, linkers, and lone pairs determining the framework geometries of mixed metal oxides is analyzed. The second factor considers the regulation of crystallographic centricity determined by the availability of hydrogen-bonding interactions between anionic frameworks containing local asymmetric polyhedra and organic cations. Finally, the third factor explores the framework architecture and the space group symmetry influenced by the flexibility of polyhedra revealing variable coordination numbers. The centricity and framework of new solid-state materials might be controlled by using a variety of synthetically controllable asymmetric units such as organic structure-directing cations and linkers with different sizes and functional groups.

YCu(TeO3)2(NO3)(H2O)3: a novel layered tellurite

A new hydrated yttrium copper tellurite nitrate, yttrium(III) copper(II) bis-[trioxidotellurate(IV)] nitrate trihydrate, has been synthesized hydro-thermally in a Teflon-lined autoclave and structurally determined using synchrotron radiation. The new phase is the first example containing yttrium, copper and tellurium in one structure. Its crystal structure is unique, with relatively strongly bound layers extending parallel to (020), defined by YO8, CuO4 and TeO3 polyhedra, while the NO3 (-) anions and one third of the water mol-ecules lie between those layers. The structural unit consists of [Cu2(TeO3)4](4-) loop-branched chains of {Cu⋯Te⋯Cu⋯Te} squares running parallel to [001], which are linked further into layers only through Y(O,H2O)8 polyhedra. Weak 'secondary' Te bonds and O-H⋯O hydrogen-bonding inter-actions, involving water mol-ecules and layer O atoms, link the layers and inter-layer species. IR spectroscopic data are also presented.