An orthorhombic polymorph of 2-(1,3,5-dithiazinan-5-yl)ethanol or MEA-dithiazine

Substituted triazines are a class of compounds utilized for scavenging and sequestering hydrogen sulfide in oil and gas production operations. The reaction of one of these triazines under field conditions resulted in the formation of the title compound, 2-(1,3,5-dithiazinan-5-yl)ethanol, C5H11NOS2, or MEA-dithiazine. Polymorphic form I, in space group I41/a, was first reported in 2004 and its extended structure displays one-dimensional, helical strands connected through O—H...O hydrogen bonds. We describe here the form II polymorph of the title compound, which crystallizes in the orthorhombic space group Pbca as centrosymmetric dimers through pairwise O—H...N hydrogen bonds from the hydroxyl moiety to the nitrogen atom of an adjacent molecule.

Synthesis, characterization and crystal structure of 4-methoxybenzylidene-based zinc(II) complexes

Two novel zinc(II) complexes containing 4-methoxybenzylidene moieties namely, Zn(L)Cl2 (L = N, N′-bis(4-methoxybenzylidene)ethane-1, 2-diamine (1) or N-(4-methoxybenzylidene)-ethane-1, 2-diamine (2)) have been synthesized and characterized by infrared spectroscopy and single-crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic space group P21/c with a = 9.2315(4); b = 12.0449(4); c = 18.2164(7) Å; β = 98.472(4)°, V = 1278.9(4) Å3 and Z = 4. Complex 2 crystallizes in the monoclinic space group P21/n with a = 6.5733 (2), b = 13.6595(5), c = 15.1615(5) Å; β = 101.846(4)°, V = 1332.33(8) Å3 and Z = 4. The environment of each Zn(II) atom is distorted tetrahedral with coordination of two terminal Cl atoms and two N atoms of the N,N′ – bis(4-methoxybenzylidene)ethane-1,2-diamine (1) or N-(4-methoxybenzylidene)ethane-1,2-diamine (2) ligand. The stability of the crystalline structure is ensured by the existence of intra- and intermolecular hydrogen bonds of the type C–H…Cl (1) and N–H…Cl (2) leading to supramolecular topologies.

Novel Fluoridoaluminates from Ammonothermal Synthesis: Two Modifications of K2AlF5 and the Elpasolite Rb2KAlF6

Two new modifications of the pentafluoridoaluminate K2AlF5 were obtained from ammonothermal synthesis at 753 K, 224 MPa and 773 K, 220 MPa, respectively. Both crystallize in the orthorhombic space group type Pbcn, with close metric relations and feature kinked chains of cis-vertex-connected AlF6 octahedra resulting in the Niggli formula ∞1{[AlF2/2eF4/1t]2−}. The differences lie in the number of octahedra necessary for repetition within the chains, which for K2AlF5-2 is realized after four and for K2AlF5-3 after eight octahedra. As a result, the orthorhombic unit cell for K2AlF5-3 is doubled in chain prolongation direction [001] as compared to K2AlF5-2 (1971.18(4) pm versus 988.45(3) pm, respectively), while the unit cell parameters within the other two directions are virtually identical. Moreover, the new elpasolite Rb2KAlF6 is reported, crystallizing in the cubic space group Fm3¯m with a = 868.9(1) pm and obtained under ammonothermal conditions at 723 K and 152 MPa.

Topological phase transition associated with structural phase transition in ternary half Heusler compound LiAuBi.

In this article, we report detailed theoretical investigations of topological phases in a new non-centrosymmetric half Heusler compound LiAuBi upto a pressure of 30 GPa. It is found that the compound forms into a dynamically stable face centered cubic (FCC) lattice structure of space group F ¯43m (216) at ambient pressure. The compound is topologically non-trivial at ambient pressure, but undergoes a quantum phase transition to trivial topological phase at 23.4 GPa. However, the detailed investigations show a structural phase transition from FCC lattice (space group 216) to a honeycomb lattice (space group 194) at 13 GPa, which is also associated with a non-trivial to trivial topological phase transition. Further investigations show that the compound also carries appreciable thermoelectric properties at ambient pressure. The figure of merit (ZT) increases from 0.21 at room temperature to a maximum value of 0.22 at 500K. The theoretical findings show its potential for practical applications in spintronics as well as thermoelectricity, therefore LiAuBi needs to be synthesized and investigated experimentally for its applications.

The layer silicate Cs2SnIVSi6O15

Single crystals of Cs2SnSi6O15, dicaesium tin(IV) hexasilicate, were serendipitously obtained from a CsCl/NaCl flux at 923 K, starting from mixtures of CaO, SnO and TeO2 in a closed silica ampoule. The crystal structure of Cs2SnSi6O15 is constructed from {Si6O15}6– layers extending parallel to (101), and CsI cations with a coordination number of eleven as well as isolated [SnO6] octahedra situated between the silicate layers. Each of the nine different SiO4 tetrahedra in the silicate layer has a connectedness of Q 3 (three bridging and one terminal O atom), which leads to the formation of five- and eight-membered rings. The same type of silicate layer is found in the crystal structure of the mineral zeravshanite. Comparison with other silicates of the type Cs2 M IVSi6O15 (M IV = Ti, Zr, Th, U) revealed a klassengleiche group–subgroup relationship of index 2 between Cs2ZrSi6O15 (Z = 6, space group C2/m) and Cs2SnSi6O15 (Z = 12, space group I2/c).

4-[(Benzylamino)carbonyl]-1-methylpyridinium halogenide salts: X-ray diffraction study and Hirshfeld surface analysis

Two salts of 4-[(benzylamino)carbonyl]-1-methylpyridinium (Am) with chloride (C14H15N2O+·Cl−) and bromide (C14H15N2O+·Br−) anions were studied and compared with the iodide salt. AmCl crystallizes in the centrosymmetric space group P21/n while AmBr and AmI form crystals in the Sohncke space group P212121. Crystals of AmBr are isostructural to those of AmI. The cation and anion are bound by an N–H...Hal hydrogen bond. Hirshfeld surface analysis was used to compare different types of intermolecular interactions in the three structures under study.

Interactions in ternary bismuth-containing molybdate systems M2MoO4-Bi2(MoO4)3-Zr(MoO4)2 in the subsolidus region

A fundamental problem in materials science consists in establishing a relationship between the chemical composition, structure, and properties of materials. This issue can be solved through the study of multicomponent systems and the directed synthesis of promising compounds. Of practical interest here are active dielectrics that are based on complex oxide compounds, specifically molybdates. Among complex molybdates and tungstates, ternary caged molybdates of the following structural types are of greatest importance: nasicon, perovskite, langbeinite, etc. Due to their widely varying elemental and quantitative compositions, such molybdates are convenient models for structural and chemical design, as well as the establishment of “composition–structure– properties” genetic relationships. Bismuth-containing complex molybdate systems exhibit the formation of phases having ferro-piezoelectric, ionic, and other properties. In this work, the Rb2MoO4–Bi2(MoO4)3–Zr(MoO4)2 ter nary salt system was studied for the first time using the method of intersecting sections in the subsolidus region (450–650 ℃). To this end, quasibinary sections were identified; triangulation was performed. Ternary molybdates Rb5BiZr(MoO4)6 and Rb2BiZr2(MoO4)6,5 were formed in the system using a ceramic technology. These compounds are isostructural to the previously obtained REE molybdates (M5LnZr(MoO4)6) but contain trivalent bismuth instead of rare earth elements. The structure of Rb5BiZr(MoO4)6 was adjusted via the Rietveld refinement technique using the TOPAS 4.2 software package. The ternary molybdate crystallizes in a trigonal system, with the following unit cell parameters of the R`3c space group: a = 10.7756(2) and c = 39.0464(7) Å. According to the studies of thermal properties exhibited by M5BiZr(MoO4)6, these ternary molybdates undergo the first-order phase transition in the temperature range of 450–600 ºC. The IR and Raman spectra of M5BiZr(MoO4)6 reveal the crystallization of ternary molybdates in the R`3c space group. The conducted comparative characterization of M2MoO4–Bi2(MoO4)3–Zr(MoO4)2 phase diagrams suggests that the phase equilibria of these systems depend on the nature of molybdates of monovalent elements.

Synthesis and characterization of a uranium oxide hydrate framework with Sr(II) ions: Structural insights and mixed uranium valences

A mixed-valence uranium oxide hydrate framework with Sr2+ ions (UOF-Sr2) was synthesized hydrothermally and characterized with multiple structural and spectroscopic techniques. Compound UOF-Sr2 crystallizes in monoclinic space group C2/c, having...

Crystallographic characterization of three cathinone hydrochlorides new on the NPS market: 1-(4-methylphenyl)-2-(pyrrolidin-1-yl)hexan-1-one (4-MPHP), 4-methyl-1-phenyl-2-(pyrrolidin-1-yl)pentan-1-one (α-PiHP) and 2-(methylamino)-1-(4-methylphenyl)pentan-1-one (4-MPD)

Cathinones belong to a group of compounds of great interest in the new psychoactive substances (NPS) market. Constant changes to the chemical structure made by the producers of these compounds require a quick reaction from analytical laboratories in ascertaining their characteristics. In this article, three cathinone derivatives were characterized by X-ray crystallography. The investigated compounds were confirmed as: 1-[1-(4-methylphenyl)-1-oxohexan-2-yl]pyrrolidin-1-ium chloride (1, C17H26NO+·Cl−, the hydrochloride of 4-MPHP), 1-(4-methyl-1-oxo-1-phenylpentan-2-yl)pyrrolidin-1-ium chloride (2; C16H24NO+·Cl−, the hydrochloride of α-PiHP) and methyl[1-(4-methylphenyl)-1-oxopentan-2-yl]azanium chloride (3; C13H20NO+·Cl−, the hydrochloride of 4-MPD). All the salts crystallize in a monoclinic space group: 1 and 2 in P21/c, and 3 in P21/n. To the best of our knowledge, this study provides the first detailed and comprehensive crystallographic data on salts 1–3.