Tetrahedral Coordination Research Articles

The influence of redox state on the location of iron ions in the structure of silicate glass with high iron content

With the help of Mössbauer investigations, it was found that tetrahedral coordination is present in the alkali silicate glass system for both Fe2+ and Fe3+ in oxidising molten glass. The reduction process changes the coordination number of iron from 4 to 6. It is clear that the iron content has a much stronger influence on the properties than the redox state. In lower temperatures, the difference between reducing and oxidising conditions can be clearly observed, which at high temperatures lies within the measurement error range. A change in the redox state has a significant influence on the transition temperature, density, microhardness, and on the expansion coefficient. Therefore, it can be concluded that after reduction, the iron ions in the structure play a similar role to that of network transducers.

Solution combustion synthesis, characterization, magnetic, and dielectric properties of CoFe2O4 and Co0.5M0.5Fe2O4 (M = Mn, Ni, and Zn).

Nanocrystalline CoFe2O4 and Co0.5M0.5Fe2O4 (M = Mn, Ni, and Zn) ferrites were prepared by the solution combustion method using oxalyl dihydrazide as a fuel. These materials were characterized by several physicochemical techniques. X-ray diffraction (XRD) patterns indicate the cubic spinel structure of these ferrites. Field emission scanning electron microscopy (FESEM) images demonstrate the microporous nature of the materials because of the large amount of gas production during their synthesis. High resolution transmission electron microscopy (HRTEM) images show lattice fringes corresponding to the {220} and {311} planes of the spinel structure. Fourier transform infrared (FTIR) spectra exhibit absorption bands around the 500-600 cm-1 wavenumber region which are related to metal-oxygen bonds with tetrahedral coordination. Symmetric and asymmetric stretching and symmetric bending modes associated with tetrahedral and octahedral cations present in the spinel structures have been assessed by Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) studies demonstrate the presence of Co2+, Mn2+, Ni2+, Zn2+, and Fe3+ in tetrahedral and octahedral coordinations in these ferrites. Co0.5Zn0.5Fe2O4 is observed to show the highest saturation magnetization among all these materials. The dielectric measurements reveal that the dielectric constant and loss values decrease with an increase in frequency and the ac conductivity increases at higher frequencies due to mobilization of the charge carriers.

Molecular mechanism of Be2+-ion binding to HLA-DP2: tetrahedral coordination, conformational changes and multi-ion binding.

The chemistry of beryllium is rather unusual, however, less explored as compared to other main group elements. This is mainly attributed to the high toxicity of beryllium, leading to chronic granulomatous pneumonitis, called chronic beryllium disease (CBD). It has been reported that Be2+-ion binding to the human leukocyte antigen protein (HLA-DP2) and peptide (M2) results in favorable interaction with the T-cell receptor protein (TCR), which initiates immune-mediated toxicity. We have carried out molecular dynamics (MD) simulations combined with quantum mechanical/molecular mechanical (QM/MM) studies to explore the binding nature of Be2+ with a HLA-DP2 protein and M2 peptide. The interaction between the negatively charged M2 peptide and the negatively charged binding cleft of HLA-DP2 is unfavorable. However, this interaction is stabilized by one Be2+ and two Na+-ions bridged by negatively charged carboxyl groups of glutamate residues (β26E and β69E) of the β-chain of HLA-DP2 and one glutamate (p7E) and one aspartate residue (p4D) of the M2 peptide. This multi-ion cavity consists of tetrahedrally coordinated static Be2+ and Na+-ions, as well as one dynamically exchangeable Na+-ion. The smaller size and higher charge of the Be2+-ion as compared to the Na+-ion reduce the distance between the M2 peptide and the β-chain of HLA-DP2, which results in conformational change suitable for TCR binding. However, the replacement of the Be2+ by the Na+-ion could not generate a suitable binding site for TCR.

Probing the electronic boundaries between trigonal and tetrahedral coordination at beryllium.

NEt3 adducts to BeCl2, BeBr2 and BeI2 were synthesized and characterised via NMR and IR spectroscopy as well as X-ray diffractometry. Depending on the halide and the state of matter these are either mono- or dinuclear. Population analyses were performed to determine the influence of the metal's partial charge on the coordination geometry. Additionally, the reactivity of these compounds towards C-Cl- and O-H-bonds was studied.

Crystallographic Changes Accompanying the Verwey Transition in a Magnetite from Steatite

The crystallographic structural analysis of the magnetite of a steatite rock at 298 K, (saturation magnetization, σ = 95.0 J T-1 kg-1) showed two cubic networks and, below Verwey temperature (TV ca.120 K) a monoclinic structure, basing on their cell dimensions and different transitional behaviors when reducing the temperature. A monoclinic structure was identified from their cell dimensions and different transition behaviors when reducing the temperature. The average chemical formula of this almost stoichiometric magnetite was deduced from the chemical analysis, 298 K-Mossbauer and the structural refinement. The Rietveld fitting of the 298 K X-ray pattern is Fe3+Fe0.953+Fe0.882+Cr0.043+Al0.043+Mg0.052+Ni0.022+⊗0.02O4, where [ ] and { } stand for cations in tetrahedral and octahedral coordination symmetries, respectively. The crystallographic structure below TV in this magnetite was observed from synchrotron X-ray diffraction data (XRD), collected at 15 K. It was identified three structures: two cubic (space group, Fd3m), with significantly different lattice parameters, and one monoclinic (P2/c).

An in-depth study of Sn substitution in Li-rich/Mn-rich NMC as a cathode material for Li-ion batteries.

Layered Li-rich/Mn-rich NMC (LMR-NMC) is characterized by high initial specific capacities of more than 250 mA h g-1, lower cost due to a lower Co content and higher thermal stability than LiCoO2. However, its commercialisation is currently still hampered by significant voltage fade, which is caused by irreversible transition metal ion migration to emptied Li positions via tetrahedral interstices upon electrochemical cycling. This structural change is strongly correlated with anionic redox chemistry of the oxygen sublattice and has a detrimental effect on electrochemical performance. In a fully charged state, up to 4.8 V vs. Li/Li+, Mn4+ is prone to migrate to the Li layer. The replacement of Mn4+ for an isovalent cation such as Sn4+ which does not tend to adopt tetrahedral coordination and shows a higher metal-oxygen bond strength is considered to be a viable strategy to stabilize the layered structure upon extended electrochemical cycling, hereby decreasing voltage fade. The influence of Sn4+ on the voltage fade in partially charged LMR-NMC is not yet reported in the literature, and therefore, we have investigated the structure and the corresponding electrochemical properties of LMR-NMC with different Sn concentrations. We determined the substitution limit of Sn4+ in Li1.2Ni0.13Co0.13Mn0.54-xSnxO2 by powder X-ray diffraction and transmission electron microscopy to be x≈ 0.045. The limited solubility of Sn is subsequently confirmed by density functional theory calculations. Voltage fade for x = 0 and x = 0.027 has been comparatively assessed within the 3.00 V-4.55 V (vs. Li/Li+) potential window, from which it is concluded that replacing Mn4+ by Sn4+ cannot be considered as a viable strategy to inhibit voltage fade within this window, at least with the given restricted doping level.

Crystal and mol-ecular structures of a binuclear mixed ligand complex of silver(I) with thio-cyanate and 1H-1,2,4-triazole-5(4H)-thione.

The complete mol-ecule of the binuclear title complex, bis-[μ-1H-1,2,4-triazole-5(4H)-thione-κ2 S:S]bis-{(thio-cyanato-κS)[1H-1,2,4-triazole-5(4H)-thione-κS]silver(I)}, [Ag2(SCN)2(C2H3N3S)4], is generated by crystallographic inversion symmetry. The independent triazole-3-thione ligands employ the exocyclic-S atoms exclusively in coordination. One acts as a terminal S-ligand and the other in a bidentate (μ2) bridging mode to provide a link between two AgI centres. Each AgI atom is also coordinated by a terminal S-bound thio-cyanate ligand, resulting in a distorted AgS4 tetra-hedral coordination geometry. An intra-molecular N-H⋯S(thio-cyanate) hydrogen bond is noted. In the crystal, amine-N-H⋯S(thione), N-H⋯N(triazol-yl) and N-H⋯N(thio-cyanate) hydrogen bonds give rise to a three-dimensional architecture. The packing is consolidated by triazolyl-C-H⋯S(thio-cyanate), triazolyl-C-H⋯N(thiocyanate) and S⋯S [3.2463 (9) Å] inter-actions as well as face-to-face π-π stacking between the independent triazolyl rings [inter-centroid separation = 3.4444 (15) Å]. An analysis of the calculated Hirshfeld surfaces shows the three major contributors are due to N⋯H/H⋯N, S⋯H/H⋯S and C⋯H/H⋯C contacts, at 35.8, 19.4 and 12.7%, respectively; H⋯H contacts contribute only 7.6% to the overall surface.

Steering polyoxometalate transformation from octahedral to tetrahedral coordination by counter-cations.

Polyoxometalates (POMs) are intriguing catalysts for various reactions. However, the function of their counter-cations is overlooked. Here, we show that flexible counter-cations of methyltrioctylammonium can trigger polyoxovanadates to transform from octahedrally coordinated H2V10O284- to tetrahedrally coordinated V10O262-. This structural transformation enhances the performance tunability of POM chemistry and improves catalyst design.

A self-penetrated three-dimensional zinc(II) coordination framework based on 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzoic acid and 1,3-bis[(imidazol-1-yl)methyl]benzene ligands: synthesis, structure and properties.

With the rapid development of metal-organic frameworks (MOFs), a variety of MOFs and their derivatives have been synthesized and reported in recent years. Commonly, multifunctional aromatic polycarboxylic acids and nitrogen-containing ligands are employed to construct MOFs with fascinating structures. 4,4',4''-(1,3,5-Triazine-2,4,6-triyl)tribenzoic acid (H3TATB) and the bidentate nitrogen-containing ligand 1,3-bis[(imidazol-1-yl)methyl]benzene (bib) were selected to prepare a novel ZnII-MOF under solvothermal conditions, namely poly[[tris{μ-1,3-bis[(imidazol-1-yl)methyl]benzene}bis[μ3-4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzoato]trizinc(II)] dimethylformamide disolvate trihydrate], {[Zn3(C24H12N3O6)2(C14H14N4)3]·2C3H7NO·3H2O}n (1). The structure of 1 was characterized by single-crystal X-ray diffraction, IR spectroscopy and powder X-ray diffraction. The properties of 1 were investigated by thermogravimetric and fluorescence analysis. Single-crystal X-ray diffraction shows that 1 belongs to the monoclinic space group Pc. The asymmetric unit contains three crystallographically independent ZnII centres, two 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzoate (TATB3-) anions, three complete bib ligands, one and a half free dimethylformamide molecules and three guest water molecules. Each ZnII centre is four-coordinated and displays a distorted tetrahedral coordination geometry. The ZnII centres are connected by TATB3- anions to form an angled ladder chain with large windows. Simultaneously, the bib ligands link ZnII centres to give a helical Zn-bib-Zn chain. Furthermore, adjacent ladders are bridged by Zn-bib-Zn chains to form a fascinating three-dimensional self-penetrated framework with the short Schläfli symbol 65·7·813·9·10. In addition, the luminescence properties of 1 in the solid state and the fluorescence sensing of metal ions in suspension were studied. Significantly, compound 1 shows potential application as a fluorescent sensor with sensing properties for Zr4+ and Cu2+ ions.

Синтез и строение гексабромоплатината циклопропилтрифенилфосфония

Using the interaction of potassium hexabromoplatinate with cyclopropyltriphenylphosphonium bromide in acetonitrile after crystallization from dimethyl sulfoxide, the [Ph 3 PC 3 H 5 ] 2 [PtBr 6 ] complex ( 1 ) has been obtained for the first time (red crystals, m.p. 235 °C). The compound 1 has been characterized by IR-spectroscopy and X-ray analysis. According to the data of X-ray analysis the unit cell crystallographic parameters of compound 1 are: orthorhombic syngony, the symmetry group Pna2 1 ; M 1281.22; cell parameters: a = 14.653(6), b = 18.874(8), c = 15.921(8) Å; a = 90.00 degrees, β = 90.00 degrees, g = 90.00 degrees; V = 4403(3) Å 3 ; ρ (calc.) = 1.933 g/cm 3 , Z = 8, the crystal size is 0.32×0.24×0.16 mm; intervals of reflection indexes –25 ≤ h ≤ 25, –17 ≤ k ≤ 19, –21 ≤ l ≤ 20; total reflections 66507; independent disclosures 10802; μ = 8.733 mm –1 ; R 1 = 0.0344; wR 2 = 0.0755 (all date), R 1 = 0.0484; wR 2 = 0.0807 ( F 2 > 2s( F 2 )); residual electron density 1,28/–2,05 e/Å 3 . In cations, the phosphorus atoms have a distorted tetrahedral coordination (the CPC angles equal 88.6(3)°-122.4(3)°, the P-C bond lengths are 1.541(5)-2.273(7) Å). The platinum atoms are coordinated by six bromine atoms in the anion (the BrPtBr trans -angles are close to 180°, the BrPtBr cis -angles have the values 89.17(4)-108.(3)°, the Pt-Br bond lengths are 2.1618(9)-2.9732(14) Å). Complete tables of coordinates of atoms, bond lengths and valence angles are deposited at the Cambridge Structural Data (№ 1969775; http://www.ccdc. cam.ac.uk).

Templated syntheses of heterometal tungsten-cobalt-sulfur clusters with different nuclearities.

A series of new W-Co-S clusters have been synthesized utilizing the complex [Et4N][(Tp*)WS3] (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate(1-)) as the synthetic template, by rational control of the stoichiometry of reactants and by employment of a reductant or precipitant as an auxiliary reagent. By solubility control or addition of a precipitant to avoid the involvement of Cl- in the reaction, the cluster [(Tp*)WS3]2Co (2) could be obtained. With different ratios of the Co source to the template, together with the use of an appropriate amount of reducing reagent, clusters [{(Tp*)WS3}2Co]1- (3) and [{(Tp*)WS3}2Co2Cl]1- (4) could be synthesized as their Et4N+ salts, and [{(Tp*)WS3}2Co4Cl2(DMF)]1- (5) could be isolated as its [Co(DMF)6]2+ salt. A common structural feature of these clusters is that they all have a pair of [(Tp*)WS3] templates chelating different numbers of Co atoms to form W-Co-S clusters with distinct nuclearities. The clusters [(Tp*)WS3]2Co (2) and [{(Tp*)WS3}2Co]1- (3) both have one Co atom chelated by two [(Tp*)WS3] templates, and the difference lies in not only the oxidation states but also the fact that the Co atom in 2 adopts an octahedral coordination environment while that in 3 bears a tetrahedral coordination sphere, which means that the [(Tp*)WS3] template is tri-dentate in 2 and bi-dentate in 3. The cluster [{(Tp*)WS3}2Co2Cl]1- (4) has two Co atoms chelated by a pair of [(Tp*)WS3] templates, in which one of the Co atoms is also terminally bound by a Cl- ligand. There are four Co atoms chelated by two [(Tp*)WS3] templates in the cluster [{(Tp*)WS3}2Co4Cl2(DMF)]1- (5), two of which are bound terminally by the Cl- ligands. Studies of redox properties by cyclic voltammetry indicate the existence of two reversible redox pairs related to clusters 2 and 3, respectively.

Syntheses and structural characterization of two zinc coordination polymers composed of polycarboxylate and N-donor ligands

Two zinc coordination polymers with the formulas [Zn(btec)0.5(L1)]n (1) and [Zn(4-npa)(L2)]n (2) ((L1 = bis(4-(1H-imidazol-1-yl)phenyl)methanone, L2 = bis(4-(1H-benzo[d]imidazol-1-yl)phenyl)methanone, 4-H2npa = 4-nitrophthalic acid, H4btec = 1,2,4,5-benzenetetracarboxylic acid) are synthesized and structurally characterized. The single crystal X-ray diffraction analysis shows that Zn1 in 1 is four-coordinated by two carboxylate oxygen atoms of two different betc4– ligands in a μ1-η1:η0 monodentate coordination mode and two nitrogen atoms from two L1 ligands to give a slightly distorted tetrahedral coordination geometry. The complex possesses a 4-connected net topology with the point symbol {65·8}. In 2, Zn1 has a distorted tetrahedral geometry with two O atoms from two 4-npa2– ligands and two N atoms from two L2 ligands. The [Zn(4-npa)]2 units are linked with each other by the L2 ligands to form a 2D network.

Bulky Schiff-base ligand supported Co(ii) single-ion magnets with zero-field slow magnetic relaxation.

Two mononuclear Co(ii) complexes with tetrahedral coordination geometry have been constructed from different bulky Schiff-base ligands. Both complexes exhibit slow magnetic relaxation without a static field and their relaxation behaviors can be tuned by ligand substitution. Clear magnetic hysteresis loops were observed for both complexes at 2 K.

Synthesis and Characterization of Three New Emissive Mononuclear CuI Heteroleptic Complexes with Functionalized 6-Cyano-2,2′-bipyridine Chelating Ligands

A new series of luminescent mononuclear CuI complexes with functionalized 6-cyano-2,2′-bipyridine chelating ligands, [Cu(xantphos)(cbpy)]ClO4 (1), [Cu(xantphos)(4,4’-Me2cbpy)]ClO4·CH2Cl2·H2O (2), and [Cu(POP)(cbpy)]ClO4·CH2Cl2 (3) (xantphos=4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; POP=bis(2-diphenylphosphinophenyl)ether; 4,4’-Me2cbpy=4,4’-dimethyl-6-cyano-2,2′-bipyridine; cbpy=6-cyano-2,2′-bipyridine) have been successfully prepared, and their structures and photophysical properties are investigated. Single crystal structures of the three complexes reveal a distorted tetrahedral coordination geometry around the CuI centres with the P atoms of diphosphane ligands and N donors of 2,2′-bipyridine ring. Luminescence measurements indicate that these CuI complexes display good emission properties both in the solution and solid states at room temperature, which can be well modulated through modifying the structure of 6-cyano-2,2′-bipyridine. It is shown that the introduction of two electron-donating methyl groups at the 4,4’-positions of the 6-cyano-2,2′-bipyridine is favourable to enhance the luminescence properties of the CuI complexes.

Effect of the iron content on the structure and electrical properties of sodium borosilicate glasses: XRD, TEM, Mössbauer, FTIR and DIS spectroscopy study

The iron-bearing sodium borosilicate glasses with different contents of iron were prepared by the charge melting method and studied by XRD, TEM, FTIR, Mössbauer and Dynamic Impedance Spectroscopy techniques. An analysis and the transmittance spectra of two-phase sodium borosilicate glasses with different contents of iron oxide were carried out. A usage of the Mössbauer spectroscopy revealed differences between two-phase and porous glasses. In both cases Fe2+ and Fe3+ ions in octahedral and tetrahedral coordination were found, while in the two-phase glasses the significant contribution of magnetite was additionally detected. The activation energy associated with the relaxation processes determined from the electric modulus spectra was found to be in a range between 0.986 eV and 0.729 eV, which is close to the activation energy for dc conductivity. Two different conduction mechanisms were observed and their physical origin was explained. The hopping between two valence states of iron and the sodium ion conduction mechanism was additionally discussed.

A Computational and Structural Database Study of the Metal-Carbene Bond in Groups IA, IIA, and IIIA Imidazol-2-Ylidene Complexes

Imidazol-2-ylidenes are important N-heterocyclic carbenes which have become universal ligands in organometallic and coordination chemistry. Generally classified as σ-donor ligands, these compounds have been used to stabilize various metal complexes which hitherto were less stable in their catalytic processes. Herein, the number and distribution of group IA, group IIA, and group IIIA metal-imidazol-2-ylidene complexes retrieved from the Cambridge Structural Database (CSD) are assessed. The data showed that the mean M-Ccarbene bond length increases with increasing ionic size but is similar across each diagonal. Dominant factors such as Lewis acidity and electrostatic attractions were found to control the bonding modes of the respective ions. Generally, the metal ions show preference for tetrahedral coordination with larger cations forming complexes with higher coordination numbers. For their high number of entries (101), tetrahedrally coordinated boron complexes with various electron withdrawing and electron donating groups were studied computationally at the DFT/B3LYP level of theory. The strength of the B-Ccarbene bond was found to depend on steric interactions between bulky groups on the borenium atom and substituents on the N-positions of the imidazol-2-ylidene ligand. This observation was further confirmed by estimation of the binding energy, natural charge, and the electron distribution in the B-Ccarbene bond.

Synthesis, characterization and biological assay of three new benzotriazole-based Zn(II) complexes

Three new Zn(II) complexes, namely [Zn(emimb)2Cl2] (1), [Zn(dmimb)2Cl2] (2) and [Zn(bmem)2(SCN)2] (3), have been synthesized using the benzotriazole-based ligands, 1-((2-ethyl-4-methyl-1H-imidazol-1-yl)methyl)-1H-benzotriazole (emimb), 1-((2,4-dimethyl-1H-imidazol-1-yl)methyl)-1H-benzotriazole (dmimb) and 1-((2-ethyl-1H-imidazol-1-yl)methyl)-1H-benzotriazole (bmem). All the complexes were fully characterized by elemental analysis, IR spectroscopy, 1H NMR spectroscopy and single-crystal X-ray diffraction analysis. Complexes 1–3 show mononuclear structures and the central Zn(II) ion of 1–3 is four-coordinated in a distorted tetrahedral coordination geometry. Complex 2 presents an interesting 3-D network through two different intermolecular π-π stacking interactions. The antidiabetic activities against α-amylase of ligands and complexes 1–3 are investigated in vitro. The results indicate that the three Zn(II) complexes inhibit α-amylase more strongly than free ligands. Antioxidant tests in vitro show that the complex 3 possesses a mild antioxidant activity against 1,1-diphenyl-picrylhydrazyl (DPPH). In addition, the solid-state photoluminescence properties of ligands and their Zn(II) complexes have been investigated.

IR and NMR Studies of the Status of Al and Acid Sites in Desilicated Zeolite Y.

The desilication of zeolite Y (of Si/Al = 31) that was previously dealuminated by steaming and acid treatment was studied. Desilication of zeolites of high Si/Al module in alkali solutions extracts both Si and Al from zeolite crystals, but while Si remains in solution, Al is reinserted into the zeolite grain. The main goal of our study was to follow the status of Al reinserted into zeolite during the desilication procedure, and its role in the formation of acid sites of the Brønsted and Lewis types. The properties of Al were followed by 27Al MAS NMR spectroscopy (for parent samples and zeolites treated either with NaOH or NaOH/tetrabutylammonium hydroxide), whereas the acid sites generated in the final stages were studied by IR spectroscopy with NH3 and CO as probe molecules. In non-desilicated zeolite, most of the Al was in a typically zeolitic tetrahedral coordination, while both NMR and quantitative IR studies of NH3 sorption evidenced that Al that was extracted by desilication and was subsequently reinserted had a tetrahedral coordination similar to amorphous aluminosilicates and showed an ion exchange ability. After the exchange of Na+ to NH4+ and decomposition of NH4+ ions, reinserted Al forms generated protonic sites from which some condensed at higher temperatures producing Lewis acid sites (with stoichiometry typical for zeolites i.e., the condensation of two protonic sites produces one Lewis site) but some other kept their character.

X-ray absorption spectroscopy study of cobalt mononitride thin films

We present a comprehensive study to resolve the debate about the structure of cobalt mononitride (CoN). In contradiction with theoretical predictions, experimentally CoN has been claimed to synthesize in a rock-salt (RS) and in a zinc-blende (ZB)-type structure under ambient pressure and temperature. Utilizing X-ray absorption near-edge spectroscopy (XANES) at Co and N K-edges and extended X-ray absorption fine structure (EXAFS) at Co K-edge, we investigated the structure of CoN in detail. The presence of a strong pre-edge feature at the Co K-edge and the absence of t $$_2$$ feature at the N K-edge indicate towards the tetrahedral coordination that is expected in the ZB-type structure of CoN. Theoretical simulations of XANES spectra unambiguously confirm the ZB-type structure in CoN. Also from EXAFS data, we found that Co–N and Co–Co bond distances match well with ZB-CoN. Magnetic properties of CoN were examined using polarized neutron reflectivity and bulk magnetization measurements. It was found that CoN sample exhibits a paramagnetic behaviour as expected in ZB-CoN. Obtained results clearly demonstrate that CoN indeed crystalizes in the ZB-type structure, and the possibility of the RS-type CoN can be ruled out under ambient pressure and temperature. It is anticipated that the information about the structure of CoN can be utilized for its usage in emerging areas such as low-cost catalyst in oxygen and hydrogen evaluation reactions, high capacity anode in ion batteries and in photovoltaic applications.

CRYSTAL STRUCTURE OF THE COMPOUNDS CuGa2S(Se)3I

One of the directions for finding new materials is to complicate the component composition of the compounds. Therefore, the acquisition of new tetrachloride halogens and the study of their crystalline structure have become the object of this search. Ternary and quaternary chalcohenides and chalcоhalohenides with tetrahedral coordination cations are among the classes of compounds that are of great interest to researchers. The tetrahedral compounds of the composition AB2X3Y are formed in the systems AY – B 2 X 3 (where A – Cu, Ag; B – In; X – S, Se, Te; Y – Cl, Br, I). Our attention was focused on the compounds where A is Cu, B is Ga; X is S, Se; Y is I). By the X-ray phase analysis method, the existence of new quaternary compounds CuGa 2 S 3 I, CuGa 2 Se 3 I have been established and their crystal structures have been studied by the powder method. Compounds were synthesized by a direct single-temperature method from simple substances of copper, galium, sulfur, and freshly obtained copper (I) iodide. Sulfur had been previously cleaned by a twotime vacuum distillation method. The crystal structures of these compounds were determined from data sets obtained on the DRON 4-13 X-ray diffractometer (CuKα radiation, in the range of 10°≤2θ≤100°, scan step 0.05°, 20 sec. exposure at each point). The computation of the crystal structure of the quaternary compounds CuGa 2 S 3 I, CuGa 2 Se 3 I was performed using WinCSD software package. Compounds CuGa2S3I, CuGa2Se3I have been indexed in tetragonal syngony, space group I-4 with cell parameters: a= 0.3311 (2) nm, c= 1.04411 (5) nm for the sulfur-containing compound, a= 0.55821 (3) nm, c= 1.0981 (2) nm for the selenium-containing compound. The unit cell contains 14 atoms. The coordinates of the atoms and the isotropic displacement parameters have satisfactory values. In the structures of the compounds, the galium atoms occupy two regular point positions (2a and 2c) and have tetrahedral environments [Ga 14 S(Se) 1 ], [Ga 24 S(Se) 1 ]. The positions of Ga 1 (2a) and Ga 2 (2c) are 80% filled. The statistical mixtures M1 (Cu + Ga) and M2 (Cu + Ga) occupy two regular point systems (2b and 2d) and are surrounded by the tetrahedra [M 14 S(Se) 1 ], [M 24 S(Se) 1 ]. The statistical mixtures M 1 (2b) and M 2 (2d) have the following composition: 50% Cu and 20% Ga, 30% of the position is not filled.