Synthesis, structure, and electronic structure of K2CuSbS3

The new compound K₂CuSbS₃ has been synthesized by the reaction of K₂S, Cu, Sb, and S at 823 K. The compound crystallizes in the Na₂CuSbS₃ structure type with four formula units in space group P2₁/c of the monoclinic system in a cell at 153 K of a=6.2712 (6) Å, b=17.947 (2) Å, c=7.4901 (8) Å, β=120.573 (1)°, and V=725.81 (12) Å³. The structure contains two-dimensional layers separated by K atoms. Each layer is built from CuS₃ and SbS₃ units. Each Cu atom is pyramidally coordinated to three S atoms with the Cu atom about 0.4 Å above the plane of the S atoms. Each Sb atom is similarly coordinated to three S atoms but is about 1.1 Å above its S₃ plane. First-principles calculations indicate an indirect band gap of 1.9 eV. These calculations also indicate that there is a bonding interaction between the Cu and Sb atoms. An optical absorption measurement performed with light perpendicular to the (0 1 0) crystal face of a red block-shaped crystal of K₂CuSbS₃ indicates an experimental indirect band gap of 2.2 eV.     

Single-crystal growth, crystal and electronic structure of NaCoO2

Single crystals of NaCoO₂ have been successfully synthesized for the first time by a flux method at 1323 K. A single-crystal X-ray diffraction study confirmed the trigonal space group and the lattice parameters , . The crystal structure has been refined to the conventional values R=1.9% and wR=2.1% for 309 independent observed reflections. The electron density distribution of NaCoO₂ has been studied by the maximum entropy method (MEM) using single-crystal X-ray diffraction data obtained at 298 K. From the results of the MEM analysis, the strong covalent bonding was clearly observed between Co and O atoms, while no bonding was observed around Na atoms. We also calculated the electron density of NaCoO₂ by first principles calculations. The electron density obtained experimentally is in good agreement with the theoretical one.     

Synthesis, structure, and magnetic and electronic properties of Cs2Hg2USe5

The compound Cs₂Hg₂USe₅ was obtained from the solid-state reaction of U, HgSe, Cs₂Se₃, Se, and CsI at 1123 K. This material crystallizes in a new structure type in space group P2/n of the monoclinic system with a cell of dimensions a=10.276(6) Å, b=4.299(2) Å, c=15.432(9) Å, β=101.857(6) Å, and V=667.2(6) Å³. The structure contains layers separated by Cs atoms. Within the layers are distorted HgSe₄ tetrahedra and regular USe₆ octahedra. In the temperature range of 25-300 K Cs₂Hg₂USe₅ displays Curie-Weiss paramagnetism with μ_eff=3.71(2) μ_B. The compound exhibits semiconducting behavior in the [010] direction; the conductivity at 298 K is 3×10⁻³ S/cm. Formal oxidation states of Cs/Hg/U/Se may be assigned as +1/+2/+4/− 2, respectively.     

Synthesis, structure, band gap, and electronic structure of CsAgSb4S7

The compound CsAgSb₄S₇ has been synthesized by the reaction of the elements in a Cs₂S₃ flux at 773 K. The compound crystallizes in a new structure type with eight formula units in space group C2/c of the monoclinic system in a cell at 153 K of dimensions , , , β=97.650(1)°, and . The structure contains two-dimensional layers separated by Cs atoms. Each layer is built from edge-sharing one-dimensional and chains. Each Ag atom is tetrahedrally coordinated to four S atoms. Each Sb³⁺ center is pyramidally coordinated to three S atoms to form an SbS₃ group. CsAgSb₄S₇ is insulating with an optical band gap of 2.04 eV. Extended Hückel calculations indicate that the band gap in CsAgSb₄S₇ is dominated by the Sb 5s and S 3p states above and below the Fermi level.     

Syntheses and structures of CsHo3Te5 and Cs3Tm11Te18 and the electronic structure of CsHo3Te5

Single crystals of CsHo₃Te₅ and Cs₃Tm₁₁Te₁₈ have been grown as byproducts in the synthesis of CsLnZnTe₃ (Ln=Ho or Tm) through the reaction of Ln, Zn, and Te with a CsCl flux at 850 °C. The crystal structures have been determined from single-crystal X-ray diffraction data. CsHo₃Te₅ crystallizes in space group Pnma of the orthorhombic system whereas Cs₃Tm₁₁Te₁₈ crystallizes in the space group C2/m of the monoclinic system. Each of the compounds adopts a three-dimensional structure; each possesses tunnels built from LnTe₆ octahedra that are filled with Cs atoms. The pseudo-rectangular tunnel in CsHo₃Te₅ is large enough in cross-section to accommodate two symmetrically equivalent Cs atoms. In the Cs₃Tm₁₁Te₁₈ structure there are two different sized tunnels: the smaller one is only large enough to host one Cs atom per unit cell whereas the larger one can accommodate two Cs atoms. The electronic structure of CsHo₃Te₅ was calculated. The band gap is estimated to be about 1.2 eV, consistent with the black color of the crystals.     

Synthesis, crystal and electronic structure, and physical properties of the new lanthanum copper telluride La3Cu5Te7

The new lanthanum copper telluride La₃Cu_5−xTe₇ has been obtained by annealing the elements at 1073 K. Single-crystal X-ray diffraction studies revealed that the title compound crystallizes in a new structure type, space group Pnma (no. 62) with lattice dimensions of a=8.2326(3) Å, b=25.9466(9) Å, c=7.3402(3) Å, V=1567.9(1) Å³, Z=4 for La₃Cu_4.86(4)Te₇. The structure of La₃Cu_5−xTe₇ is remarkably complex. The Cu and Te atoms build up a three-dimensional covalent network. The coordination polyhedra include trigonal LaTe₆ prisms, capped trigonal LaTe₇ prisms, CuTe₄ tetrahedra, and CuTe₃ pyramids. All Cu sites exhibit deficiencies of various extents. Electrical property measurements on a sintered pellet of La₃Cu_4.86Te₇ indicate that it is a p-type semiconductor in accordance with the electronic structure calculations.     

Synthesis, structure, and magnetic properties of Ba2Cu2US5

The alkaline-earth uranium chalcogenide Ba₂Cu₂US₅ was obtained in a two-step reaction from BaS, Cu₂S, and US₂. Ba₂Cu₂US₅ crystallizes in a new structure type in space group C2/m of the monoclinic system with two formula units in a cell of dimensions a=13.606(3) Å, b=4.0825(8) Å, c=9.3217(19) Å, and β=116.32(3)° (153 K). The structure consists of layers separated by Ba atoms in bicapped trigonal-prismatic coordination. The two-dimensional layer is built from US₆ octahedra and CuS₄ tetrahedra. The connectivity of the MS_n polyhedra within the layer in the [001] direction is oct tet tet oct tet tet. A μ_eff value of 2.69(2) μ_B/U was obtained from the magnetic susceptibility data. No magnetic transition was observed for Ba₂Cu₂US₅ down to 2 K.     

Synthesis, structure, optical properties, and electronic structure of NaLiCdS2

The new compound NaLiCdS₂ has been synthesized by the reaction of Cd and a Li₂S/S/Na₂S flux at 773 K. This compound, which has the Ce₂O₂S structure type, crystallizes with one formula unit in space group P3¯m1 of the trigonal system in a cell at T=153 K with a=4.1320(3) Å and c=6.8666(11) Å. The structure consists of two-dimensional layers stacked perpendicular to the [001] direction. The two-dimensional layers are formed by corner-sharing LiS₄ or CdS₄ tetrahedra. The Na atoms are between these layers. Li incorporation in the compound is confirmed by an SIMS chemical composition map and by ICP measurements. The Li and Cd atoms are disordered in the crystal structure. First-principles calculations show that the optical excitations arise primarily from S→Cd charge-transfer transitions at 1.0 eV (very weak) and 2.4 eV (strong). Calculations also indicate that Na contributions around the Fermi level are significant. Polarized single-crystal optical measurements indicate an indirect optical band gap of 2.37 eV for light perpendicular to the (001) crystal face, in good agreement with theory. The compound NaLiZnS₂ has also been synthesized and is found to be isostructural with NaLiCdS₂.     

KBiMS4 (M=Si, Ge): Synthesis, structure, and electronic structure

Two new bismuth sulfides KBiSiS₄ and KBiGeS₄ have been synthesized by means of the reactive flux method. They adopt the RbBiSiS₄ structure type and crystallize in space group P2₁/c of the monoclinic system. The structure consists of (M=Si, Ge) layers separated by bicapped trigonal-prismatically coordinated K atoms. The M atom is tetrahedrally coordinated to four S atoms and the Bi atom is coordinated to a distorted monocapped trigonal prism of seven S atoms. The optical band gap of 2.25(2) eV for KBiSiS₄ was deduced from the diffuse reflectance spectrum. From a band structure calculation, the optical absorption for KBiSiS₄ originates from the layer. The Si 3p orbitals, Bi 6p orbitals, and S 3p orbitals are highly hybridized near the Fermi level. The orbitals of K have no contributions on both the upper of valence band and the bottom of conduction band.     

Synthesis and crystal structure of EuBi2

The new hypervalent binary phase EuBi₂ was obtained from high temperature solid-state reactions of the pure metal elements in welded Ta tubes under argon atmosphere. Its structure was established by single-crystal X-ray diffraction. The title compound crystallizes in the tetragonal space group I4₁/amd (No. 141) with cell parameters of , and Z=8. The structure of EuBi₂ is isotypic with HfGa₂ and features 1D Bi⁻ zigzag anionic chains along both a- and b-axes and 2D Bi⁻ square sheets normal to c-axis. It can be formulated as Eu²⁺(Bi)_chain⁻(Bi)_square⁻.     

Synthesis and crystal structure of a novel ternary oxoborate, PbBiBO4

A novel ternary borate oxide, lead bismuth boron tetraoxide, PbBiBO₄, has been prepared by solid-state reaction at temperature below 800 °C. The single-crystal X-ray structural analysis showed that PbBiBO₄ crystallizes in the monoclinic space group P2₁/n with , , , β=91.48(1), Z=4. It represents a new structure type in which distorted BiO₆⁹⁻ octahedra are connected to each other in corner- and edge-sharing manner to form two-dimensional layers that are bridged by B atoms of BO₃ triangles giving rise to a three-dimensional framework, with channels parallel to the [0 1 0] direction accommodating the pyramidally coordinated Pb²⁺ cations.     

Synthesis and crystal structure of Ru-supported tungstoantimonate [Sb2W20Ru2(H2O)2(dmso)6O68]

The first Ru^III-supported tungstoantimonate [Ru^II(bpy)₃]₂[Sb₂W₂₀Ru^III₂(H₂O)₂(dmso)₆O₆₈]·3dmso (bpy=bi-pyridine) (1a) has been successfully isolated as [Ru(bpy)₃]²⁺ (Rubpy) salt by routine synthetic reaction in mixed solutions with dmso and water. Single-crystal X-ray analysis was carried out on 1a, which crystallizes in the triclinic system space group P-1 with a=16.804 (6), b=16.988 (6), c=17.666 (6) Å, α=107.397 (13)°, β=106.883 (13)°, γ=103.616 (12)°. V=4309 (3) Å³, Z=1 with R1=0.0773. The compound 1a reveals the following features: (1) Rubpy is firstly used as an alternative ruthenium-source for the synthesis of Ru-substituted heteropolytungstate; (2) the structure of 1a consists of four Ru^III-O-S(CH₃)₂ and two W-O-S(CH₃)₂ bonds resulting in an assembly with C₂ symmetry; (3) the Ru^III ions are linked to two dmso groups via two Ru^III-O-S(CH₃)₂ bonds, which represents the other dmso-coordination mode to Ru^III in POM chemistry. The cyclic voltammetry studies of 1a in dmso/H₂SO₄ (3/1 v/v) at pH 2.5 medium using the glassy carbon electrode as a working electrode show the respective electrochemical behaviors of the W-centers and the Ru-centers within 1a, which could be separated clearly. In addition, the compound 1a exhibits photoluminescence arising from π*−t_2g ligand-to-metal transition of Rubpy.     

Dodecanuclear rhenium cluster complexes with an interstitial carbon atom: Synthesis, structures and properties of two new compounds K6[Re12CS17(OH)6]·4H2O and Na12Re12CS17(SO3)6·48.5H2O

The dodecanuclear rhenium anionic complex with terminal hydroxo ligands [Re₁₂CS₁₇(OH)₆]⁶⁻ was obtained by the reaction of K₆[Re₁₂CS₁₇(CN)₆]·20H₂O with molten KOH at 300 °C. The cluster complex was crystallized as a potassium salt from aqueous solution. The reaction between K₆[Re₁₂CS₁₇(OH)₆]·4H₂O and Na₂S₂O₄ in water under reflux results in the formation of the complex Na₁₂[Re₁₂CS₁₇(SO₃)₆]·48.5H₂O. Both new compounds were characterized by single-crystal X-ray diffraction, elemental analyses and IR spectroscopy. The electronic structure of [Re₁₂CS₁₇(OH)₆]⁶⁻ was also elucidated by DFT calculations.     

An organosilyl derivative of trivacant tungstophosphate. Synthesis, characterization and crystal structure determination of α-A-[NBu4]3[PW9O34(C2H5SiO)3(C2H5Si)]

In the presence of NBu₄ⁿBr acting as phase-transfer reagent, organosilicon trichloride C₂H₅SiCl₃ reacts in acetonitrile with the trivacant tungstophosphate sodium salt β-A-Na₈H[PW₉O₃₄]·24H₂O to give hybrid organosilyl polyoxotungstate derivative α-A-[NBu₄ⁿ]₃[PW₉O₃₄(C₂H₅SiO)₃(C₂H₅Si)]. X-ray single crystal structural analysis indicates that the title compound is monoclinic, space group Cc, with lattice constants a=26.828(5), b=22.459(5), c=17.517(4) Å, β=103.19(3)°, V=10,276(4) Å³, Z=4, R=0.0462. According to the result of X-ray single crystal diffraction and chemical analysis, the hybrid polyanion consists of one α-A-[PW₉O₃₄]⁹⁻ framework on which are grafted simultaneously three RSiO groups through six Si-O-W bridge bonds, each of which is attached to the fourth RSi group through three Si-O-Si bridge bonds. The hybrid polyanion becomes a partial saturated, closed cage structure and also has an assembly of virtual C_3V symmetry.     

Crystal structure, electronic structure and physical properties of the new low-valent thallium silicon telluride Tl6Si2Te6 in comparison to Tl6Ge2Te6

The title compounds were prepared from the elements in the stoichiometric ratio at 800 °C under exclusion of air. Tl₆Si₂Te₆ crystallizes in the space group P1¯, isostructural with Tl₆Ge₂Te₆, with , , , α=89.158(2)°, β=96.544(2)°, γ=100.685(2)°, (Z=2). Its structure is composed of dimeric [Si₂Te₆]⁶⁻ units with a Si-Si single bond, while the Tl atoms are irregularly coordinated by five to six Te atoms. Numerous weakly bonding Tl-Tl contacts exist. Both title compounds are black semiconductors with small band gaps, calculated to be 0.9 eV for Tl₆Si₂Te₆ and 0.5 eV for Tl₆Ge₂Te₆. The Seebeck coefficients are +65 μV K⁻¹ in case of Tl₆Si₂Te₆ and +150 μV K⁻¹ in case of Tl₆Ge₂Te₆ at 300 K, and the electrical conductivities are 5.5 and 3 Ω⁻¹ cm⁻¹, respectively.     

Synthesis, crystal structure, and nonlinear optical properties of Bi2Cu5B4O14

Bi₂Cu₅B₄O₁₄ crystallizes in the noncentrosymmetric triclinic space group P1 (No. 1) with cell parameters a=10.1381(11) Å, b=9.3917(11) Å, c=3.4566(4) Å, α=105.570(2)°, β=92.275(2)°, γ=107.783(2)°, Z=1 and R₁=0.0401 and wR₂=0.0980. It is a layered structure that is built up from sheets of rectangular CuO₄ and trigonal BO₃ groups. The sheets are connected by infinite chains of edge shared BiO₆ polyhedra that intersect the bc plane at an angle slightly greater than 90°. The second-harmonic generation efficiency of Bi₂Cu₅B₄O₁₄, using 1064 nm radiation, is about one half times that of KH₂PO₄.     

Synthesis, crystal structure and characterization of iron pyroborate (Fe2B2O5) single crystals

Single crystals of iron(II) pyroborate, Fe₂B₂O₅, were prepared at 1000–1050 °C under an argon atmosphere. The crystals were transparent, yellowish in color and needle-like or columnar. The crystal structure of Fe₂B₂O₅ was analyzed by single-crystal X-ray diffraction. Refined triclinic unit cell parameters were a=3.2388(2), b=6.1684(5), c=9.3866(8) Å, α=104.613(3)°, β=90.799(2)° and γ=91.731(2)°. The final reliability factors of refinement were R1=0.020 and wR2=0.059 [I > 2σ(I)]. Transmittance over 50% in the visible light region from 500 to 750 nm was observed for a single crystal of Fe₂B₂O₅ with a thickness of about 0.3 mm. The light absorption edge estimated from a diffuse reflectance spectrum was at around 350 nm (3.6 eV). Magnetic susceptibility was measured for single crystals at 4–300 K. Fe₂B₂O₅ showed antiferromagnetic behavior below the Néel temperature, T_N≈70 K, and the Weiss temperature was T_W=36 K. The effective magnetic moment of Fe was 5.3μ_B.     

Synthesis and characterization of ionic organotin compounds [R2SnCl2(2-quin)](HNEt3) and crystal structures of [(2,4-Cl2-C6H3CH2)2SnCl2(2-quin)](HNEt3)

Eight ionic organotin compounds [R₂SnCl₂(2-quin)]⁻(HNEt₃)⁺ have been synthesized by reactions of 2-quinH with R₂SnCl₂ (R = PhCH₂1, 2-Cl-C₆H₄CH₂2, 4-Cl-C₆H₄CH₂3, 2-F-C₆H₄CH₂4, 4-F-C₆H₄CH₂5, 4-CN-C₆H₄CH₂6, Ph 7, 2,4-Cl₂-C₆H₃CH₂8) in the presence of organic base NEt₃, and their structures have been characterized by elemental analysis, IR and multinuclear NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopies. The structure of [(2,4-Cl₂-C₆H₃CH₂)₂SnCl₂(2-quin)]⁻(NEt₃)⁺ (8) has been determined by X-ray diffraction study. Studies show that compound 8 has a monomeric structure with the central tin atom six-coordinate in a distorted octahedral configuration and the nitrogen atoms of the 2-quin ligands are coordinating to the tin atom in all the eight compounds.     

Crystal structure, vibrational properties and luminescence of NaMg3Al(MoO4)5 crystal doped with Cr ions

Crystals of NaMg₃Al(MoO₄)₅ doped with 0.5% Cr³⁺ ions have been synthesized and characterized by a single-crystal X-ray structure analysis and IR, Raman, electron absorption and luminescence spectroscopic studies. It has been shown that NaMg₃Al(MoO₄)₅ crystallizes in the structure, with a=6.8744(8) Å, b=6.9342(7) Å, c=17.605(2) Å, α=87.788(8)°, β=87.727(9)°, γ=78.501(9)°, Z=2. The characteristic feature of the structure is its enormously large thermal displacement parameter for sodium, even at 105 K. The IR and Raman spectra indicate significant interactions between the MoO₄²⁻ ions in the structure. The electron absorption, excitation and luminescence studies have shown that there are at least two different sites of incorporated Cr³⁺ ions in the NaMg₃Al(MoO₄)₅ crystal structure. They differ themselves by strength of crystalline field. One of them is characterized by Cr³⁺ in low ligand field and ⁴T₂→⁴A₂ emission whereas the second is characterized by higher strength of the crystal field and dominant ²E→⁴A₂ emission. Temperature-dependent studies show that the compound does not exhibit any phase transition.     

Crystal and electronic structure of the red semiconductor Ba4LaSbGe3Se13 comprising the complex anion [Ge2Se7-Sb2Se4-Ge2Se7]

Ba₄LaGe₃SbSe₁₃ was prepared by reacting the elements under exclusion of air at 700°C, followed by slow cooling to room temperature. It crystallizes in a new type of the monoclinic space group P2₁/c, with lattice dimensions of a=1633.30(9) pm, b=1251.15(7) pm, c=1303.21(7) pm, β=103.457(2)°, V=2590.0(2) 10⁶ pm³ (Z=4). The structure contains isolated GeSe₄ as well as Ge₂Se₇ digermanate units. Two of the latter are interconnected via an Sb₂Se₄ bridge yielding an almost linear complex anion [Ge₂Se₇-Sb₂Se₄-Ge₂Se₇]¹⁴⁻. The oxidation states are assigned to be Ba^II, La^III, Ge^IV, Sb^III, and Se^−II, in accord with an electronically saturated nonmetal. The lone pair of Sb^III reflects itself in highly irregular Se coordination. The red color of the material is indicative of semiconducting behavior with an activation energy of 2.0 eV. Electronic structure calculations based on the LMTO approximation point to a smaller gap, typical for this calculation method. We utilized the COHP tool to explore the bonding character of the different Sb-Se interactions.