Li9Al4Sn5 as a new ordered superstructure of the Li13Sn5 type

Alloys from the ternary Li–Al–Sn system have been investigated with respect to possible applications as negative electrode materials in Li‐ion batteries. This led to the discovery of a new ternary compound, a superstructure of the Li₁₃Sn₅ binary compound. The ternary stannide, Li₉Al₄Sn₅ (nonalithium tetraaluminium pentastannide; trigonal, P m 1, hP18 ), crystallizes as a new structure type, which is an ordered variant of the binary Li₁₃Sn₅ structure type. One Li and one Sn site have m . symmetry, and all other atoms occupy sites of 3m . symmetry. The polyhedra around all types of atoms are rhombic dodecahedra. The electronic structure was calculated by the tight‐binding linear muffin‐tin orbital atomic spheres approximation method. The electron concentration is higher around the Sn and Al atoms, which form an [Al₄Sn₅]^m− polyanion.     

Crystal,electronic structure and hydrogenation properties of the Mg5.57Ni16Ge7.43 cluster phase with a new type of polyhedron

The ternary germanide Mg_5.57Ni₁₆Ge_7.43 (cubic, space group Fmm, cF116) belongs to the structural family based on the Th₆Mn₂₃-type. The Ge1 and Ge2 atoms fully occupy the 4a (mm symmetry) and 24d (m.mm) sites, respectively. The Ni1 and Ni2 atoms both fully occupy two 32f sites (.3m symmetry). The Mg/Ge statistical mixture occupies the 24e site with 4m.m symmetry. The structure of the title compound contains a three-core-shell cluster. At (0,0,0), there is a Ge1 atom which is surrounded by eight Ni atoms at the vertices of a cube and consequently six Mg atoms at the vertices of an octahedron. These surrounded eight Ni and six Mg atoms form a [Ge1Ni₈(Mg/Ge)₆] rhombic dodecahedron with a coordination number of 14. The [GeNi₈(Mg/Ge)₆] rhombic dodecahedron is encapsulated within the [Ni₂₄] rhombicuboctahedron, which is again encapsulated within an [Ni₃₂(Mg/Ge)₂₄] pentacontatetrahedron; thus, the three-core-shell cluster [GeNi₈(Mg/Ge)₆@Ni₂₄@Ni₃₂(Mg/Ge)₂₄] results. The pentacontatetrahedron is a new representative of Pavlyuk's polyhedra group based on pentagonal, tetragonal and trigonal faces. The dominance of the metallic type of bonding between atoms in the Mg_5.57Ni₁₆Ge_7.43 structure is confirmed by the results of the electronic structure calculations. The hydrogen sorption capacity of this intermetallic at 570 K reaches 0.70 wt% H₂.     

X‐ray and neutron powder diffraction analyses of Gly·MgSO4·5H2O and Gly·MgSO4·3H2O,and their deuterated counterparts

We have identified a new compound in the glycine–MgSO₄–water ternary system, namely glycine magnesium sulfate trihydrate (or Gly·MgSO₄·3H₂O) {systematic name: catena‐poly[[tetraaquamagnesium(II)]‐μ‐glycine‐κ²O:O′‐[diaquabis(sulfato‐κO)magnesium(II)]‐μ‐glycine‐κ²O:O′]; [Mg(SO₄)(C₂D₅NO₂)(D₂O)₃]_n}, which can be grown from a supersaturated solution at ∼350 K and which may also be formed by heating the previously known glycine magnesium sulfate pentahydrate (or Gly·MgSO₄·5H₂O) {systematic name: hexaaquamagnesium(II) tetraaquadiglycinemagnesium(II) disulfate; [Mg(D₂O)₆][Mg(C₂D₅NO₂)₂(D₂O)₄](SO₄)₂} above ∼330 K in air. X‐ray powder diffraction analysis reveals that the trihydrate phase is monoclinic (space group P2₁/n), with a unit‐cell metric very similar to that of recently identified Gly·CoSO₄·3H₂O [Tepavitcharova et al. (2012). J. Mol. Struct. 1018 , 113–121]. In order to obtain an accurate determination of all structural parameters, including the locations of H atoms, and to better understand the relationship between the pentahydrate and the trihydrate, neutron powder diffraction measurements of both (fully deuterated) phases were carried out at 10 K at the ISIS neutron spallation source, these being complemented with X‐ray powder diffraction measurements and Raman spectroscopy. At 10 K, glycine magnesium sulfate pentahydrate, structurally described by the `double' formula [Gly(d₅)·MgSO₄·5D₂O]₂, is triclinic (space group P, Z = 1), and glycine magnesium sulfate trihydrate, which may be described by the formula Gly(d₅)·MgSO₄·3D₂O, is monoclinic (space group P2₁/n, Z = 4). In the pentahydrate, there are two symmetry‐inequivalent MgO₆ octahedra on sites of symmetry and two SO₄ tetrahedra with site symmetry 1. The octahedra comprise one [tetraaquadiglcyinemagnesium]²⁺ ion (centred on Mg1) and one [hexaaquamagnesium]²⁺ ion (centred on Mg2), and the glycine zwitterion, NH₃⁺CH₂COO⁻, adopts a monodentate coordination to Mg2. In the trihydrate, there are two pairs of symmetry‐inequivalent MgO₆ octahedra on sites of symmetry and two pairs of SO₄ tetrahedra with site symmetry 1; the glycine zwitterion adopts a binuclear–bidentate bridging function between Mg1 and Mg2, whilst the Mg2 octahedra form a corner‐sharing arrangement with the sulfate tetrahedra. These bridged polyhedra thus constitute infinite polymeric chains extending along the b axis of the crystal. A range of O—H…O, N—H…O and C—H…O hydrogen bonds, including some three‐centred interactions, complete the three‐dimensional framework of each crystal.     

Li4Ge2B as a new derivative of the Mo2B5 and Li5Sn2 structure types

Binary and multicomponent intermetallic compounds based on lithium and p‐elements of Groups III–V of the Periodic Table are useful as modern electrode materials in lithium‐ion batteries. However, the interactions between the components in the Li–Ge–B ternary system have not been reported. The structure of tetralithium digermanium boride, Li₄Ge₂B, exhibits a new structure type, in the noncentrosymmetric space group R3m, in which all the Li, Ge and B atoms occupy sites with 3m symmetry. The title structure is closely related to the Mo₂B₅ and Li₅Sn₂ structure types, which crystallize in the centrosymmetric space group Rm. All the atoms in the title structure are coordinated by rhombic dodecahedra (coordination number = 14), similar to the atoms in related structures. According to electronic structure calculations using the tight‐binding–linear muffin‐tin orbital–atomic spheres approximation (TB–LMTO–ASA) method, strong covalent Ge—Ge and Ge—B interactions were established.     

Planarity of heteroaryldithiocarbazic acid derivatives showing tuberculostatic activity: structure–activity relationships

The search for new tuberculostatics is an important issue due to the increasing resistance of Mycobacterium tuberculosis to existing agents and the resulting spread of the pathogen. Heteroaryldithiocarbazic acid derivatives have shown potential tuberculostatic activity and investigations of the structural aspects of these compounds are thus of interest. Three new examples have been synthesized. The structure of methyl 2‐[amino(pyridin‐3‐yl)methylidene]hydrazinecarbodithioate, C₈H₁₀N₄S₂, at 293 K has monoclinic (P2₁/n) symmetry. It is of interest with respect to antibacterial properties. The structure displays N—H…N and N—H…S hydrogen bonding. The structure of N′‐(pyrrolidine‐1‐carbonothioyl)picolinohydrazonamide, C₁₁H₁₅N₅S, at 100 K has monoclinic (P2₁/n) symmetry and is also of interest with respect to antibacterial properties. The structure displays N—H…S hydrogen bonding. The structure of (Z)‐methyl 2‐[amino(pyridin‐2‐yl)methylidene]‐1‐methylhydrazinecarbodithioate, C₉H₁₃N₄S₂, has triclinic (P) symmetry. The structure displays N—H…S hydrogen bonding.     

Promising solid electrolyte material for an IT‐SOFC: crystal structure of the cerium gadolinium holmium oxide Ce0.8Gd0.1Ho0.1O1.9 between 295 and 1023 K

The crystal structure of Ce_0.8Gd_0.1Ho_0.1O_1.9 (cerium gadolinium holmium oxide) has been determined from powder X‐ray diffraction data. This is a promising material for application as a solid electrolyte for intermediate‐temperature solid oxide fuel cells (IT‐SOFCs). Nanoparticles were prepared using a novel sodium alginate sol‐gel method, where the sodium ion was exchanged with ions of interest and, after washing, the gel was calcined at 723 K in air. The crystallographic features of Gd and Ho co‐doped cerium oxide were investigated around the desired operating temperatures of IT‐SOFCs, i.e. 573 ≤ T ≤ 1023 K. We find that the crystal structure is a stable fluorite structure with the space group Fmm in the entire temperature range. In addition, the trend in lattice parameters shows that there is a monotonic increase with increasing temperature.     

Triethanolaminate iron perchlorate revisited: change of space group,chemical composition and oxidation states in [Fe7(tea)3(tea‐H)3](ClO4)2 (tea‐H3 is triethanolamine)

The X‐ray crystal structure of tris[N‐(2‐hydroxyethyl)‐2,2′‐iminodiethanolato]tris(2,2′,2′′‐nitrilotriethanolato)tetrairon(II)triiron(III) bis(perchlorate), [Fe₇(C₆H₁₂NO₃)₃(C₆H₁₃NO₃)₃](ClO₄)₂ or [Fe₇(tea)₃(tea‐H)₃](ClO₄)₂ (tea‐H₃ is triethanolamine), is known from the literature [Liu et al. (2008). Z. Anorg. Allg. Chem. 634 , 778–783] as a heptanuclear coordination cluster. The space group was given as I2₁3 and is reinvestigated in the present study. We find a new space‐group symmetry of Pa and could detect O—H hydrogens, which were missing in the original publication. Consequences on the Fe oxidation states are investigated with the bond‐valence method, resulting in a mixed‐valence core of four Fe^II and three Fe^III centres. Symmetry relationships between the two space groups and the average supergroup Ia are discussed in detail.     

Crystallographic study of self‐organization in the solid state including quasi‐aromatic pseudo‐ring stacking interactions in 1‐benzoyl‐3‐(3,4‐dimethoxyphenyl)thiourea and 1‐benzoyl‐3‐(2‐hydroxypropyl)thiourea

1‐Benzoylthioureas contain both carbonyl and thiocarbonyl functional groups and are of interest for their biological activity, metal coordination ability and involvement in hydrogen‐bond formation. Two novel 1‐benzoylthiourea derivatives, namely 1‐benzoyl‐3‐(3,4‐dimethoxyphenyl)thiourea, C₁₆H₁₆N₂O₃S, (I), and 1‐benzoyl‐3‐(2‐hydroxypropyl)thiourea, C₁₁H₁₄N₂O₂S, (II), have been synthesized and characterized. Compound (I) crystallizes in the space group P , while (II) crystallizes in the space group P 2₁/c . In both structures, intramolecular N—H…O hydrogen bonding is present. The resulting six‐membered pseudo‐rings are quasi‐aromatic and, in each case, interact with phenyl rings via stacking‐type interactions. C—H…O, C—H…S and C—H…π interactions are also present. In (I), there is one molecule in the asymmetric unit. Pairs of molecules are connected via two intermolecular N—H…S hydrogen bonds, forming centrosymmetric dimers. In (II), there are two symmetry‐independent molecules that differ mainly in the relative orientations of the phenyl rings with respect to the thiourea cores. Additional strong hydrogen‐bond donor and acceptor –OH groups participate in the formation of intermolecular N—H…O and O—H…S hydrogen bonds that join molecules into chains extending in the [001] direction.     

Site Preference of Cations and Structural Variation in MgAl2–xGaxO4 (0 ≤ x ≤ 2) Spinel Solid Solution

The crystal structures of MgAl_2–xGa_xO₄ (0 ≤ x ≤ 2) spinel solid solutions (x = 0.00, 0.38, 0.76, 0.96, 1.52, 2.00) were refined using ²⁷Al MAS NMR measurements and single crystal X‐ray diffraction technique. Site preferences of cations were investigated. The inversion parameter (i) of MgAl₂O₄ (i = 0.206) is slightly larger than given in previous studies. It is considered that the difference of inversion parameter is caused by not only the difference of heat treatment time but also some influence of melting with a flux. The distribution of Ga³⁺ is little affected by a change of the temperature from 1473 K to 973 K. The degree of order‐disorder of Mg²⁺ or Al³⁺ between the fourfold‐ and sixfold‐coordinated sites is almost constant against Ga³⁺ content (x) in the solid solution. A compositional variable of the Ga/(Mg + Ga) ratio in the sixfold‐coordinated site has a constant value through the whole compositional range: the ratio is not influenced by the occupancy of Al³⁺. The occupancy of Al³⁺ is independent of the occupancy of Ga³⁺, though it depends on the occupancy of Mg²⁺ according to thermal history. The local bond lengths were estimated from the refined data of solid solutions. The local bond length between specific cation and oxygen corresponds with that expected from the effective ionic radii except local Al–O bond length in the fourfold‐coordinated site and local Mg–O bond length in the sixfold‐coordinated site. The local Al–O bond length in the fourfold‐coordinated site (1.92 Å) is about 0.15 Å longer than the expected bond length. This difference is induced by a difference in site symmetry of the fourfold‐coordinated site. The nature that Al³⁺ in spinel structure occupies mainly the sixfold‐coordinated site arises from the character of Al³⁺ itself. The local Mg–O bond length in the sixfold‐coordinated site (2.03 Å) is about 0.07 Å shorter than the expected one. Difference Fourier synthesis for MgGa₂O₄ shows a residual electron density peak of about 0.17 e/ų in height on the center of (Ga_0.59 Mg_0.41)–O bond. This peak indicates the covalent bonding nature of Ga–O bond on the sixfold‐coordinated site in the spinel structure.     

Synthesis and crystal structure of a new Cu3Au‐type ternary phase in the Au–In–Pd system: distribution of atoms over crystallographic positions

A new Cu₃Au‐type ternary phase (τ phase) is found in the AuPd‐rich part of the Au–In–Pd system. It has a broad homogeneity range based on extensive (Pd,Au) and (In,Au) replacement, with the composition varying between Au_17.7In_25.3Pd_57.0 and Au_50.8In_16.2Pd_33.0. The occupancies of the crystallographic positions were studied by single‐crystal X‐ray diffraction for three samples of different composition. The sites with mm symmetry are occupied by atoms with a smaller scattering power than the atoms located on 4/mmm sites. Two extreme structure models were refined. Within the first, the occupation type changes from (Au,In,Pd)₃(Pd,In) to (Au,Pd)₃(In,Pd,Au) with an increase in the Au gross content. For the second model, the occupation type (Au,In,Pd)₃(Pd,Au) remains essentially unchanged for all Au concentrations. Although the diffraction data do not allow the choice of one of these models, the latter model, where Au substitutes In on 4/mmm sites, seems to be preferable, since it agrees with the fact that the homogeneity range of the τ phase is inclined to the Au corner and provides the same occupation type for all the studied samples of different compositions.     

Synthesis,crystal structure and magnetic properties of diaquabis(2,6‐diamino‐7H‐purin‐1‐ium‐κN9)bis(4,4′‐oxydibenzoato‐κO)cobalt(II) dihydrate

The title mononuclear Co^II complex, [Co(C₅H₇N₆)₂(C₁₄H₈O₅)₂(H₂O)₂]·2H₂O, has been synthesized and its crystal structure determined by X‐ray diffraction. The complex crystallizes in the triclinic space group P, with one formula unit per cell (Z = 1 and Z′ = ). It consists of a mononuclear unit with the Co^II ion on an inversion centre coordinated by two 2,6‐diamino‐7H‐purin‐1‐ium cations, two 4,4′‐oxydibenzoate anions (in a nonbridging κO‐monodentate coordination mode, which is less common for the anion in its Co^II complexes) and two water molecules, defining an octahedral environment around the metal atom. There is a rich assortment of nonbonding interactions, among which a strong N⁺—H…O⁻ bridge, with a short N…O distance of 2.5272 (18) Å, stands out, with the H atom ostensibly displaced away from its expected position at the donor side, towards the acceptor. The complex molecules assemble into a three‐dimensional hydrogen‐bonded network. A variable‐temperature magnetic study between 2 and 300 K reveals an orbital contribution to the magnetic moment and a weak antiferromagnetic interaction between Co^II centres as the temperature decreases. The model leads to the following values: A (crystal field strength) = 1.81, λ (spin‐orbit coupling) = −59.9 cm⁻¹, g (Landé factor) = 2.58 and zJ (exchange coupling) = −0.5 cm⁻¹.     

LiBC3: a new borocarbide based on graphene and heterographene networks

Li–B–C alloys have attracted much interest because of their potential use in lithium‐ion batteries and superconducting materials. The formation of the new compound LiBC₃ [lithium boron tricarbide; own structure type, space group P m 2, a = 2.5408 (3) Å and c = 7.5989 (9) Å] has been revealed and belongs to the graphite‐like structure family. The crystal structure of LiBC₃ presents hexagonal graphene carbon networks, lithium layers and heterographene B/C networks, alternating sequentially along the c axis. According to electronic structure calculations using the tight‐binding linear muffin‐tin orbital‐atomic spheres approximations (TB–LMTO–ASA) method, strong covalent B—C and C—C interactions are established. The coordination polyhedra for the B and C atoms are trigonal prisms and for the Li atoms are hexagonal prisms.     

Improving the Electrochemical Performance of the Li4Ti5O12 Electrode in a Rechargeable Magnesium Battery by Lithium–Magnesium Co‐Intercalation

Rechargeable magnesium batteries have attracted recent research attention because of abundant raw materials and their relatively low‐price and high‐safety characteristics. However, the sluggish kinetics of the intercalated Mg²⁺ ions in the electrode materials originates from the high polarizing ability of the Mg²⁺ ion and hinders its electrochemical properties. Here we report a facile approach to improve the electrochemical energy storage capability of the Li₄Ti₅O₁₂ electrode in a Mg battery system by the synergy between Mg²⁺ and Li⁺ ions. By tuning the hybrid electrolyte of Mg²⁺ and Li⁺ ions, both the reversible capacity and the kinetic properties of large Li₄Ti₅O₁₂ nanoparticles attain remarkable improvement.     

Deep hydration of an Li7–3xLa3Zr2MIIIxO12 solid-state electrolyte material: a case study on Al- and Ga-stabilized LLZO

Single crystals of an Li-stuffed, Al- and Ga-stabilized garnet-type solid-state electrolyte material, Li₇La₃Zr₂O₁₂ (LLZO), have been analysed using single-crystal X-ray diffraction to determine the pristine structural state immediately after synthesis via ceramic sintering techniques. Hydrothermal treatment at 150 °C for 28 d induces a phase transition in the Al-stabilized compound from the commonly observed cubic Iad structure to the acentric I3d subtype. Li^I ions at the interstitial octahedrally (4 + 2-fold) coordinated 48e site are most easily extracted and Al^III ions order onto the tetrahedral 12a site. Deep hydration induces a distinct depletion of Li^I at this site, while the second tetrahedral site, 12b, suffers only minor Li^I loss. Charge balance is maintained by the incorporation of H^I, which is bonded to an O atom. Hydration of Ga-stabilized LLZO induces similar effects, with complete depletion of Li^I at the 48e site. The Li^I/H^I exchange not only leads to a distinct increase in the unit-cell size, but also alters some bonding topology, which is discussed here.     

Nd4.67Ru3Mg8.83 – A Magnesium‐rich Compound with Ru@Mg4Nd4 Square Antiprisms and Mg@Mg8 Cubes as ­Basic Building Units

The magnesium‐rich intermetallic compound Nd_4.67Ru₃Mg_8.83 was synthesized from the elements in a sealed tantalum tube in a resistance furnace. Nd_4.67Ru₃Mg_8.83 was characterized by X‐ray powder and single crystal diffraction: new structure type,I4/mmm, tI66, a = 946.0(1), c = 1789.5(4) pm, wR2 = 0.0368, 725 F² values and 36 variables. Two of the five crystallographically independent magnesium sites show a small degree of Mg/Nd mixing. The ruthenium atoms have square anti‐prismatic Nd₄Mg₄ coordination. Always six of such anti‐prisms are condensed via common edges, leading to a CsCl analogous neodymium coordination for the Mg4 atoms. The two‐dimensional networks of edge‐sharing Ru@Nd₄Mg₄ antiprisms are condensed to a three‐dimensional network via Mg5@Mg3₄Mg1₄ cubes. The extended magnesium substructure shows a broad range of Mg–Mg distances from 308 to 351 pm.     

Reactions between arylhydrazinium chlorides and 2‐chloroquinoline‐3‐carbaldehydes: molecular and supramolecular structures of a hydrazone,a 4,9‐dihydro‐1H‐pyrazolo[3,4‐b]quinoline and two 1H‐pyrazolo[3,4‐b]quinolines

Hydrazone derivatives exhibit a wide range of biological activities, while pyrazolo[3,4‐b]quinoline derivatives, on the other hand, exhibit both antimicrobial and antiviral activity, so that all new derivatives in these chemical classes are potentially of value. Dry grinding of a mixture of 2‐chloroquinoline‐3‐carbaldehyde and 4‐methylphenylhydrazinium chloride gives (E)‐1‐[(2‐chloroquinolin‐3‐yl)methylidene]‐2‐(4‐methylphenyl)hydrazine, C₁₇H₁₄ClN₃, (I), while the same regents in methanol in the presence of sodium cyanoborohydride give 1‐(4‐methylphenyl)‐4,9‐dihydro‐1H‐pyrazolo[3,4‐b]quinoline, C₁₇H₁₅N₃, (II). The reactions between phenylhydrazinium chloride and either 2‐chloroquinoline‐3‐carbaldehyde or 2‐chloro‐6‐methylquinoline‐3‐carbaldehyde give, respectively, 1‐phenyl‐1H‐pyrazolo[3,4‐b]quinoline, C₁₆H₁₁N₃, (III), which crystallizes in the space group Pbcn as a nonmerohedral twin having Z′ = 3, or 6‐methyl‐1‐phenyl‐1H‐pyrazolo[3,4‐b]quinoline, C₁₇H₁₃N₃, (IV), which crystallizes in the space group R. The molecules of compound (I) are linked into sheets by a combination of N—H…N and C—H…π(arene) hydrogen bonds, and the molecules of compound (II) are linked by a combination of N—H…N and C—H…π(arene) hydrogen bonds to form a chain of rings. In the structure of compound (III), one of the three independent molecules forms chains generated by C—H…π(arene) hydrogen bonds, with a second type of molecule linked to the chains by a second C—H…π(arene) hydrogen bond and the third type of molecule linked to the chain by multiple π–π stacking interactions. A single C—H…π(arene) hydrogen bond links the molecules of compound (IV) into cyclic centrosymmetric hexamers having (S₆) symmetry, which are themselves linked into a three‐dimensional array by π–π stacking interactions.     

Energy release characteristics of impact-initiated energetic aluminum–magnesium mechanical alloy particles with nanometer-scale structure

Aluminum–magnesium alloys, fabricated by bi-directional rotation ball milling, were used as a kind of promising solid fuel in “reactive material” that can be ignited by impact to release a large quantity of heats. Different percentages of Mg were added to Al to yield Al_90%–Mg_10% and Al_70%–Mg_30% alloys in order to probe the effect of Mg content on the microstructure and thermal reactivity of Al–Mg alloys. Structural characterization revealed that a nanometer-scale structure was formed and oxidation of as-fabricated alloy powders was faint. Moreover, as the Mg percentage increased, the particle size of alloy decreased with increasing brittleness of Al–Mg. TGA/DSC curves of the [Al_70%–Mg_30%]–O₂ system exhibited an intense exothermic peak before melting with reaction heat of 2478 J g^?1 and its weight increase reached 90.16% of its theoretical value, which contrasted clearly with 181.2 J g^?1 and 75.35% of [Al_90%–Mg_10%]–O₂ system, respectively. In addition, other than [Al_90%–Mg_10%]–Fe₂O₃ system, the [Al_70%–Mg_30%]–Fe₂O₃ system exhibited a considerable solid–solid reaction and a low activation energy. Finally, target penetration experiments were conducted and the results confirmed that a projectile composed of [Al_70%–Mg_30%]–Fe₂O₃ displayed a more complete ignition of target than that of Al–Fe₂O₃ formulation.     

Molecular tapes in the structure of isoguaninium chloride

Isoguanine, an analogue of guanine, is of intrinsic interest as a noncanonical nucleobase. The crystal structure of isoguaninium chloride (systematic name: 6‐amino‐2‐oxo‐1H,7H‐purin‐3‐ium chloride), C₅H₆N₅O⁺·Cl⁻, has been determined by single‐crystal X‐ray diffraction. Structure analysis was supported by electrostatic interaction energy (E_es) calculations based on charge density reconstructed with the UBDB databank. In the structure, two kinds of molecular tapes are observed, one parallel to (010) and the other parallel to (50). The tapes are formed by dimers of isoguaninium cations interacting with chloride anions. E_es analysis indicates that cations in one kind of tape are oriented so as to minimize repulsive electrostatic interactions.     

LaTe1.82(1): modulated crystal structure and chemical bonding of a chalcogen‐deficient rare earth metal polytelluride

Crystals of the rare earth metal polytelluride LaTe_1.82(1), namely, lanthanum telluride (1/1.8), have been grown by molten alkali halide flux reactions and vapour‐assisted crystallization with iodine. The two‐dimensionally incommensurately modulated crystal structure has been investigated by X‐ray diffraction experiments. In contrast to the tetragonal average structure with unit‐cell dimensions of a = 4.4996 (5) and c = 9.179 (1) Å at 296 (1) K, which was solved and refined in the space group P4/nmm (No. 129), the satellite reflections are not compatible with a tetragonal symmetry but enforce a symmetry reduction. Possible space groups have been derived by group–subgroup relationships and by consideration of previous reports on similar rare earth metal polychalcogenide structures. Two structural models in the orthorhombic superspace group, i.e.Pmmn(α,β,)000(?α,β,)000 (No. 59.2.51.39) and Pm2₁n(α,β,)000(?α,β,)000 (No. 31.2.51.35), with modulation wave vectors q₁ = αa* + βb* + c* and q₂ = ?αa* + βb* + c* [α = 0.272 (1) and β = 0.314 (1)], have been established and evaluated against each other. The modulation describes the distribution of defects in the planar [Te] layer, coupled to a displacive modulation due to the formation of different Te anions. The bonding situation in the planar [Te] layer and the different Te anion species have been investigated by density functional theory (DFT) methods and an electron localizability indicator (ELI‐D)‐based bonding analysis on three different approximants. The temperature‐dependent electrical resistance revealed a semiconducting behaviour with an estimated band gap of 0.17 eV.     

Crystal structure,shape analysis and bioactivity of new LiI,NaI and MgII complexes with 1,10‐phenanthroline and 2‐(3,4‐dichlorophenyl)acetic acid

Reactions of 1,10‐phenanthroline (phen) and 2‐(3,4‐dichlorophenyl)acetic acid (dcaH) with M_n(CO₃) (M = Li^I, Na^I and Mg^II; n = 1 and 2) in MeOH yield the mononuclear lithium complex aqua[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)lithium(I), [Li(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)] or [Li(dca)(phen)(H₂O)] ( 1 ), the dinuclear sodium complex di‐μ‐aqua‐bis{[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)sodium(I)}, [Na₂(C₈H₅Cl₂O₂)₂(C₁₂H₈N₂)₂(H₂O)₂] or [Na₂(dca)₂(phen)₂(H₂O)₂] ( 2 ), and the one‐dimensional chain magnesium complex catena‐poly[[[diaqua(1,10‐phenanthroline‐κ²N,N′)magnesium]‐μ‐2‐(3,4‐dichlorophenyl)acetato‐κ²O:O′] 2‐(3,4‐dichlorophenyl)acetate monohydrate], {[Mg(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)₂](C₈H₅Cl₂O₂)·H₂O}_n or {[Mg(dca)(phen)(H₂O)₂](dca)·H₂O}_n ( 3 ). In these complexes, phen binds via an N,N′‐chelate pocket, while the deprotonated dca^? ligands coordinate either in a monodentate (in 1 and 2 ) or bidentate (in 3 ) fashion. The remaining coordination sites around the metal ions are occupied by water molecules in all three complexes. Complex 1 crystallizes in the triclinic space group P with one molecule in the asymmetric unit. The Li⁺ ion adopts a four‐coordinated distorted seesaw geometry comprising an [N₂O₂] donor set. Complex 2 crystallizes in the triclinic space group P with half a molecule in the asymmetric unit, in which the Na⁺ ion adopts a five‐coordinated distorted spherical square‐pyramidal geometry, with an [N₂O₃] donor set. Complex 3 crystallizes in the orthorhombic space group P2₁2₁2₁, with one Mg²⁺ ion, one phen ligand, two dca^? ligands and three water molecules in the asymmetric unit. Both dcaH ligands are deprotonated, however, one dca^? anion is not coordinated, whereas the second dca^? anion coordinates in a bidentate fashion bridging two Mg²⁺ ions, resulting in a one‐dimensional chain structure for 3 . The Mg²⁺ ion adopts a distorted octahedral geometry, with an [N₂O₄] donor set. Complexes 1 – 3 were evaluated against urease and α‐glucosidase enzymes for their inhibition potential and were found to be inactive.