Syntheses, crystal structures and optical properties of the first strontium selenium(IV) and tellurium(IV) oxychlorides: Sr3(SeO3)(Se2O5)Cl2 and Sr4(Te3O8)Cl4

Two new quaternary strontium selenium(IV) and tellurium(IV) oxychlorides, namely, Sr₃(SeO₃)(Se₂O₅)Cl₂ and Sr₄(Te₃O₈)Cl₄, have been prepared by solid-state reaction. Sr₃(SeO₃)(Se₂O₅)Cl₂ features a three-dimensional (3D) network structure constructed from strontium(II) interconnected by Cl⁻, SeO₃²⁻ as well as Se₂O₅²⁻ anions. The structure of Sr₄(Te₃O₈)Cl₄ features a 3D network in which the strontium tellurium oxide slabs are interconnected by bridging Cl⁻ anions. The diffuse reflectance spectrum measurements and results of the electronic band structure calculations indicate that both compounds are wide band-gap semiconductors.     

Syntheses, crystal structures and characterizations of BaZn(SeO3)2 and BaZn(TeO3)Cl2

Two new barium zinc selenite and tellurite, namely, BaZn(SeO₃)₂ and BaZn(TeO₃)Cl₂, have been synthesized by the solid state reaction. The structure of BaZn(SeO₃)₂ features double chains of [Zn(SeO₃)₂]²⁻ anions composed of four- and eight-member rings which are alternatively along a-axis. The double chains of [Zn₂(TeO₃)₂Cl₃]³⁻ anions in BaZn(TeO₃)Cl₂ are formed by Zn₃Te₃ rings in which each tellurite group connects with three ZnO₃Cl tetrahedra. BaZn(SeO₃)₂ and BaZn(TeO₃)Cl₂ are wide bandgap semiconductors based on optical diffuse reflectance spectrum measurements.     

La4(Si5.2Ge2.8O18)(TeO3)4 and La2(Si6O13)(TeO3)2: Intergrowth of the lanthanum(III) tellurite layer with the XO4 (X=Si/Ge) tetrahedral layer

Two novel lanthanum(III) silicate tellurites, namely, La₄(Si_5.2Ge_2.8O₁₈)(TeO₃)₄ and La₂(Si₆O₁₃)(TeO₃)₂, have been synthesized by the solid state reactions and their structures determined by single crystal X-ray diffraction. The structure of La₄(Si_5.2Ge_2.8O₁₈)(TeO₃)₄ features a three-dimensional (3D) network composed of the [(Ge_2.82Si_5.18)O₁₈]⁴⁻ tetrahedral layers and the [La₄(TeO₃)₄]⁴⁺ layers that alternate along the b-axis. The germanate-silicate layer consists of corner-sharing XO₄ (X=Si/Ge) tetrahedra, forming four- and six-member rings. The structure of La₂(Si₆O₁₃)(TeO₃)₂ is a 3D network composed of the [Si₆O₁₃]²⁻ double layers and the [La₂(TeO₃)₂]²⁺ layers that alternate along the a-axis. The [Si₆O₁₃]²⁻ double layer is built by corner-sharing silicate tetrahedra, forming four-, five- and eight-member rings. The TeO₃²⁻ anions in both compounds are only involved in the coordination with La³⁺ ions to form a lanthanum(III) tellurite layer. La₄(Si_5.2Ge_2.8O₁₈)(TeO₃)₄ is a wide band-gap semiconductor.     

Synthesis, crystal and band structures, and properties of a new supramolecular complex (Hg2As)2(CdI4)

A new quaternary supramolecular complex (Hg₂As)₂ (CdI₄) (1) has been prepared by the solid-state reaction and structurally characterized by single crystal X-ray diffraction analysis. Compound 1 crystallizes in the space group P2₁ of the monoclinic system with two formula units in a cell: a=7.945(4), b=12.934(6), c=8.094(4) Å, β=116.898°(1), V=741.7(6) Å³. The structure of 1 is characterized by a tridymite-like three-dimensional cationic framework, which is composed of mercury and arsenic atoms, with the channels being occupied by discrete CdI₄²⁻ tetrahedral guest-anions. The optical properties were investigated in terms of the diffuse reflectance and Fourier transform infrared spectra. The electronic band structure along with density of states (DOS) calculated by DFT method indicates that the present compound is a semiconductor with a direct band gap, and that the optical absorption is mainly originated from the charge transitions from I-5p and As-4p to Cd-5s and Hg-6s states.     

Synthesis, crystal structure and optical properties of an indium phosphate K3In3P4O16

An alkali-metal indium phosphate crystal, K₃In₃P₄O₁₆, has been synthesized by a high-temperature solution reaction and exhibits a new structure in the family of the alkali-metal indium phosphates system. Single-crystal X-ray diffraction analysis shows the structure to be monoclinic with space group P2₁/n, and the following cell parameters: a=9.7003(18), b=9.8065(18), c=15.855(3) Å, β=90.346(3)°, V=1508.2(5) Å³, Z=4, R=0.0254. It possesses three-dimensional anionic frameworks with tunnels occupied by K⁺ cations running along the a-axis. The emission and absorption spectra of the compound have been investigated. Additionally, the calculations of energy band structure, density of states, dielectric constants and refractive indexes have been performed with the density functional theory method. Also, the two-photon absorption spectrum is simulated by two-band model. The obtained results tend to support the experimental data.     

Structure, energy band, and optical properties of NaLa(PO3)4 crystal

An alkali metal-rare earth phosphate crystal of NaLa(PO₃)₄ has been synthesized by high temperature solid-state reactions and structurally characterized by single crystal X-ray diffraction analysis, for the first time. It crystallizes in the monoclinic P2₁/n space group with lattice parameters: a=7.2655(3), b=13.1952(5), , β=90.382°(1), , Z=4. It is composed of LaO₈ polyhedra and [(PO₃)₄]⁴⁻ chains sharing oxygen atoms to form a three-dimensional framework, delimiting intersecting tunnels in which the sodium ions are located. The IR spectrum, absorption spectrum, and emission spectrum of the compound have been investigated. The absorption edge is located at 340 nm (3.60 eV). The calculated total and partial densities of states indicate that the top of valence bands is mainly built upon O-2p states which interact with P-3p states via σ (P-O) interactions, and the low conduction bands mostly originates from unoccupied La-5d states. The P-O bond is mostly covalent in character, and the ionic character of the Na-O bond is larger than that in the La-O bond.     

Synthesis, band structure, and optical properties of Ba2ZnV2O8

A novel compound Ba₂ZnV₂O₈ has been synthesized in high temperature solution reaction and its crystal structure has been characterized by means of single crystal X-ray diffraction analysis. It crystallizes in monoclinic system and belongs to space group P2₁/c with a=7.9050(16), b=16.149(3), , β=90.49(3). It builds up from 1-D branchy chains of [ZnV₂O₈⁴⁻]_∞, and the Ba²⁺ cations are located in the space among these chains. The IR spectrum, ultraviolet-visible diffuse reflection integral spectrum and fluorescent spectra of this compound have been investigated. The calculated results of energy band structure by the density functional theory method show that the solid-state compound of Ba₂ZnV₂O₈ is an insulator with direct band gap of 3.48 eV. The calculated total and partial density of states indicate that the top valence bands are contributions from the mixings of O-2p, V-3d, and Zn-3d states and low conduction bands mostly originate from unoccupied antibonding states between the V-3d and O-2p states. The V-O bonds are mostly covalence characters and Zn-O bonds are mostly ionic interactions, and the ionic interaction strength is stronger between the Ba-O than between the Zn-O. The refractive index of n_x, n_y, and n_z is estimated to be 1.7453, 1.7469, and 1.7126, respectively, at wavelength of 1060 nm for Ba₂ZnV₂O₈ crystal.     

Crystal structure and spectral characterization of hexanuclear oxo titanium(IV) clusters: [Ti6O6(OSi(CH3)3)6(OOCR)6] (R = Bu,CH2Bu,C(CH3)2Et)

Hexanuclear oxo titanium(IV) siloxo carboxylate complexes with the general formula [Ti₆O₆(OSi(CH₃)₃)₆(OOCR)₆] (R = Bu^t (1), CH₂Bu^t (2), C(CH₃)₂Et (3)) were synthesized in quantitative yield, by the reaction of Ti(OSiMe₃)₄ with the appropriate organic acid. Crystal structure determination revealed that molecules of 1–3 are composed of [Ti₆-(μ₃-O)₆] cores stabilized by six syn–syn carboxylato bridges and six terminal siloxide ligands. Each metal atom is surrounded by six oxo atoms, capping the triangular faces of the distorted octahedron. Spectral characterization (IR, NMR) of 1–3 revealed a significant non-equivalence of the carboxylate group interactions, resulting from the asymmetry of the Ti-μ-OOC bonds of the syn–syn bridges. The thermal stability of the studied compounds was determined from TGA/DTA analysis.     

Synthesis, crystal and band structures, and optical properties of a new supramolecular complex: [Hg6Sb4](InBr6)Br

A new supramolecular complex [Hg₆Sb₄](InBr₆)Br (1) has been prepared by the solid-state reaction of HgBr₂ with elemental In and Sb at 450 °C. The crystal structure of 1 features a three-dimensional [Hg₆Sb₄]⁴⁺ framework with cavities of two different sizes occupied by different kinds of guest anions. The bigger cavities are filled with the octahedral InBr₆³⁻ ions, while the smaller cavities trap Br⁻ ions. The optical properties were investigated in terms of the diffuse reflectance and infrared spectra. The electronic band structure along with density of states (DOS) calculated by DFT method indicates that the present compound is semiconductor, and the optical absorption is mainly originated from the charge transitions from Sb-5p and Br-4p to In-5s and Hg-6s states.     

Photochemical reaction of W(CO)6 with SnCl4 II. Synthesis and X-ray structure of tetrachlorobis(triphenylphosphine oxide)tungsten(IV), [WCl4(OPPh3)2]

The crystal structure of [WCl₄(OPPh₃)₂](1), formed in the photochemical reaction of W(CO)₆ with SnCl₄ in the presence of triphenylphosphine, has been determined by the single-crystal X-ray diffraction method. The compound crystallizes in the monoclinic space C2/c, with A=14.027(3), B=13.163(3), C=19.621(4) Å, β=96.36(3)°, Z=4. The structure solved by heavy-atom methods has been refined to R=0.0466, for 3489 observed reflections.

The [WCl₄(OPPh₃)₂] molecule possesses a crystallographically imposed C₂ axis passing through the tungsten atom. Despite steric demands, a mutually cis arrangement of triphenylphosphine oxide oxygens is found for [WCl₄(OPPh₃)₂], while there is a slight lengthening of the W---Cl bonds trans to the oxygen atoms.     

Synthesis, crystal structures and luminescence properties of the Eu-doped yttrium oxotellurates(IV) Y2Te4O11 and Y2Te5O13

Y₂Te₄O₁₁:Eu³⁺ and Y₂Te₅O₁₃:Eu³⁺ single crystals in sub-millimeter scale were synthesized from the binary oxides (Y₂O₃, Eu₂O₃ and TeO₂) using CsCl as fluxing agent. Crystallographic structures of the undoped yttrium oxotellurates(IV) Y₂Te₄O₁₁ and Y₂Te₅O₁₃ have been determined and refined from single-crystal X-ray diffraction data. In Y₂Te₄O₁₁, a layered structure is present where the reticulated sheets consisting of edge-sharing [YO₈]¹³⁻ polyhedra are interconnected by the oxotellurate(IV) units, whereas in Y₂Te₅O₁₃ only double chains of condensed yttrium-oxygen polyhedra with coordination numbers of 7 and 8 are left, now linked in two crystallographic directions by the oxotellurate(IV) entities. The Eu³⁺ luminescence spectra and the decay time from different energy levels of the doped compounds were investigated and all detected emission levels were identified. Luminescence properties of the Eu³⁺ cations have been interpreted in consideration of the now accessible detailed crystallographic data of the yttrium compounds, providing the possibility to examine the influence of the local symmetry of the oxygen coordination spheres.     

Insulin-like model complexes: Synthesis,spectra characterization and crystal structure of two novel oxovanadium complexes with poly(pyrazolyl)borate ligands VO(HB(pz)3)(H2B(pz)2) and VO(B(pz)4)2

Two new oxovanadium (IV) complexes VO(HB(pz)₃)(H₂B(pz)₂) (1) and VO(B(pz)₄)₂ (2) have been obtained by the reaction of oxovanadium sulfate with the corresponding ligands KHB(pz)₃, KH₂B(pz)₂ and KB(pz)₄, respectively. The two complexes were characterized by elemental analyses, IR, UV–Vis and X-ray diffraction. Complex 1 crystallizes in the orthorhombic space group, Pca2₁. Complex 2 crystallizes in the orthorhombic space group, Pna2₁. In both complexes, five nitrogen atoms and one oxygen atom coordinate to the vanadium atom, forming a distorted octahedral geometry (VON₅). In addition, related spectra characterization, hydrogen-binding properties, structural configuration and quantum chemistry calculations are also discussed.     

Synthesis, crystal structure and magnetic property of a new nickel selenite chloride: Ni5(SeO3)4Cl2

The new nickel selenite chloride, Ni₅(SeO₃)₄Cl₂, was obtained by high-temperature solid state reaction of NiCl₂, Ni₂O₃ and SeO₂ in a 1:2:4 molar ratio at 700 °C in an evacuated quartz tube. Its structure was established by single-crystal X-ray diffraction. Ni₅(SeO₃)₄Cl₂ crystallizes in the triclinic system, space group P-1 (No. 2) with cell parameters of a=8.076(2), b=9.288(2), c=9.376(2) Å, α=101.97(3), β=105.60(3), γ=91.83(3)° and Z=2. All nickel(II) ions in Ni₅(SeO₃)₄Cl₂ are octahedrally coordinated by selenite oxygens or/and chloride anions (([Ni(1)O₅Cl], [Ni(2)O₄Cl₂], [Ni(3)O₅Cl], [Ni(4)O₆] and [Ni(5)O₄Cl]). The structure of the title compound features a condensed three-dimensional (3D) network built by Ni(II) ions interconnected by SeO₃²⁻ anions as well as Cl⁻ anions. Magnetic property measurements show strong antiferromagnetic interaction between nickel(II) ions.     

Synthesis of Cr2(MoO4)3

Studies on the kinetics and mechanism of the reaction leading to Cr₂(MoO₄)₃ have been made using X-ray diffraction and infrared spectroscopy. The apparent activation energy, E=285±22 kJ/mol has been calculated, based on the Ginstling-Brounstein diffusion controlled model.     

Syntheses, crystal structures and optical spectroscopy of Ln2(SO4)3·8H2O (Ln=Ho, Tm) and Pr2(SO4)3·4H2O

The lanthanide sulphate octahydrates Ln₂(SO₄)₃·8H₂O (Ln=Ho, Tm) and the respective tetrahydrate Pr₂(SO₄)₃·4H₂O were obtained by evaporation of aqueous reaction mixtures of trivalent rare earth oxides and sulphuric acid at 300 K. Ln₂(SO₄)₃·8H₂O (Ln=Ho, Tm) crystallise in space group C2/c (Z=4, a_Ho=13.4421(4) Å, b_Ho=6.6745(2) Å, c_Ho=18.1642(5) Å, β_Ho=102.006(1) Å³ and a_Tm=13.4118(14) Å, b_Tm=6.6402(6) Å, c_Tm=18.1040(16) Å, β_Tm=101.980(8) Å³), Pr₂(SO₄)₃·4H₂O adopts space group P2₁/n (a=13.051(3) Å, b=7.2047(14) Å, c=13.316(3) Å, β=92.55(3) Å³). The vibrational and optical spectra of Ho₂(SO₄)₃·8H₂O and Pr₂(SO₄)₃·4H₂O are also reported.     

Synthesis, structure and cytotoxicity of diorganotin(IV) complexes of 2,6-lutidine-α,3-diol (Lu): The crystal structures of Lu and [SnMe2(H2O)(Lu-2H)]

The reaction of dimethyl-, diethyl- and dibutyltin(IV) oxide with 2,6-lutidine-α²,3-diol (Lu) [2-(hydroxymethyl)-3-hydroxy-6-methylpyridine] in toluene/ethanol has been investigated. The compounds were isolated and characterized by IR, Raman and Mössbauer spectroscopy, EI and FAB mass spectrometry and ¹H and ¹¹⁹Sn NMR spectroscopy. The structures of Lu and [SnMe₂(H₂O)(Lu-2H)] were determined by X-ray diffraction. The crystal of [SnMe₂(H₂O)(Lu-2H)] contains dimeric [SnMe₂(H₂O)(Lu-2H)]₂ units, in which the tin atom is coordinated to the O atoms of the two deprotonated hydroxymethyl groups and one deprotonated phenolic hydroxyl group. The distorted octahedral coordination polyhedron of each tin atom is completed by a water molecule and two methyl C atoms. The butyl derivative exhibited significant in vitro antitumor activity against the human carcinoma cell lines HeLa-229, A2780 and A2780cis, although minor than that of the pyridoxine derivative prepared previously.     

A sodium gadolinium phosphate with two different types of tunnel structure: Synthesis, crystal structure, and optical properties of Na3GdP2O8

A sodium gadolinium phosphate crystal, Na₃GdP₂O₈, has been synthesized by a high-temperature solution reaction, and it exhibits a new structural family of the alkali-metal-rare-earth phosphate system. Although many compounds with formula M₃LnP₂O₈ have been reported, but they were shown to be orthorhombic [R. Salmon, C. Parent, M. Vlasse, G. LeFlem, Mater. Res. Bull. 13 (1978) 439] rather than monoclinic as shown in this paper. Single-crystal X-ray diffraction analysis shows the structure to be monoclinic with space group C2/c and the cell parameters: a=27.55 (25), b=5.312 (4), c=13.935(11) Å, β=91.30(1)°, and V=2038.80 Å³, Z=4. Its structure features a three-dimensional GdP₂O₈³⁻ anionic framework with two different types of interesting tunnels at where Na atoms are located by different manners. The framework is constructed by Gd polyhedra and isolated PO₄ tetrahedra. It is different from the structure of K₃NdP₂O₈ [R. Salmon, C. Parent, M. Vlasse, G. LeFlem, Mater. Res. Bull. 13 (1978) 439] with space group P2₁/m that shows only one type of tunnel. The emission spectrum and the absorption spectrum of the compound have been investigated. Additionally, the calculations of band structure, density of states, dielectric constants, and refractive indexes have been also performed with the density functional theory method. The obtained results tend to support the experimental data.     

Synthesis, crystal structures and photoluminescence properties of new oxyborates, Mg5NbO3(BO3)3 and Mg5TaO3(BO3)3, with novel warwickite-type superstructures

Single crystals of new oxyborates, Mg₅NbO₃(BO₃)₃ and Mg₅TaO₃(BO₃)₃, were prepared at 1370 °C in air using B₂O₃ as a flux. They were colorless and transparent with block shapes. X-ray diffraction analysis of the single crystals revealed Mg₅NbO₃(BO₃)₃ and Mg₅TaO₃(BO₃)₃ to be isostructural. The X-ray diffraction reflections were indexed to the orthorhombic Pnma (No. 62) system with a=9.3682(3) Å, b=9.4344(2) Å, c=9.3379(3) Å and Z=4 for Mg₅NbO₃(BO₃)₃ and a=9.3702(3) Å, b=9.4415(3) Å, c=9.3301(2) Å and Z=4 for Mg₅TaO₃(BO₃)₃. The crystal structures of Mg₅NbO₃(BO₃)₃ and Mg₅TaO₃(BO₃)₃ are novel warwickite-type superstructures having ordered arrangements of Mg and Nb/Ta atoms. Polycrystals of Mg₅NbO₃(BO₃)₃ prepared by solid state reaction at 1200 °C in air showed broad blue-to-green emission with a peak wavelength of 470 nm under 270 nm ultraviolet excitation at room temperature.     

Synthesis,characterization and antimicrobial studies of mixed ligand silver(I) complexes of thioureas and triphenylphosphine; crystal structure of {[Ag(PPh3)(thiourea)(NO3)]2·[Ag(PPh3)(thiourea)]2(NO3)2}

Mixed ligand silver(I) complexes of triphenylphosphine and thioureas (thiourea (Tu), N-methylthiourea (Metu), N,N′-dimethylthiourea (Dmtu) and N,N′-diethylthiourea (Detu)) with the general formulae, [(Ph₃P)₂Ag(thione)]NO₃ and [(Ph₃P)Ag(thione)₂]NO₃, have been prepared and characterized by elemental analysis, IR and NMR (¹H, ¹³C and ³¹P) spectroscopic methods. The crystal structure of one of them has been determined by X-ray crystallography. The spectral data of the complexes are consistent with sulfur coordination of the thiones to silver(I). The single crystal X-ray structure of complex 1, {[Ag(PPh₃)(thiourea)(NO₃)]₂·[Ag(PPh₃)(thiourea)]₂(NO₃)₂}, shows that the complex consists of two independent centrosymmetric binuclear units, each having the silver atoms coordinated to one PPh₃ and two bridging thiourea molecules. In one of the independent units the silver atom is additionally bound to a nitrate ion, leading to a tetrahedral geometry, while in the other unit the silver atom adopts a trigonal planar environment. Antimicrobial activities of the complexes were evaluated by their minimum inhibitory concentration and the results showed that the complexes show a wide range of activity against two gram-negative bacteria (Escherichiacoli, Pseudomonasaeruginosa) and molds (Aspergillusniger, Penicilliumcitrinum), while the activities were poor against yeasts (Candidaalbicans, Saccharomycescerevisiae). However, the title complex did not show activity against any tested microorganism.     

Synthesis,crystal structure and magnetic properties of the helical oxalate-bridged copper(II) chain {[(CH3)4N]2[Cu(C2O4)2] · H2O}n

The preparation, crystal structure and magnetic properties of a new oxalate-containing copper(II) chain of formula {[(CH₃)₄N]₂[Cu(C₂O₄)₂] · H₂O}_n (1) [(CH₃)₄N⁺ = tetramethylammonium cation] are reported. The structure of 1 consists of anionic oxalate-bridged copper(II) chains, tetramethylammoniun cations and crystallization water molecules. Each copper(II) ion in 1 is surrounded by three oxalate ligands, one being bidentate and the other two exhibiting bis-bidenate coordination modes. Although all the tris-chelated copper(II) units from a given chain exhibit the same helicity, adjacent chains have opposite helicities and then an achiral structure results. Variable-temperature magnetic susceptibility measurements of 1 show the occurrence of a weak ferromagnetic interaction through the oxalate bridge [J = +1.14(1) cm⁻¹, the Hamiltonian being defined as H = –J ∑_nmS_i · S_j]. This value is analyzed and discussed in the light of available magneto-structural data for oxalate-bridged copper(II) complexes with the same out-of-plane exchange pathway.