As predicted and more: modulated channel occupation in YZn5+x
Like many complex intermetallic phases, the crystal structures of REZn5+x compounds (RE = lanthanide or Group 3 element) based on the EuMg5 type have gradually unfolded. The original reports described a complex hexagonal structure with an unusual combination of tetrahedrally close-packed regions and open spaces, as well as observations of superstructure reflections. More recently, we reinvestigated the structure of YZn5, reclassifying it as the EuMg5+x-type compound YZn5+x (x ≃ 0.2), in which disordered channels run along c through the spaces formerly considered open. In addition, DFT-chemical pressure (DFT-CP) a...
Source: Acta Crystallographica Section B - July 7, 2023 Category: Chemistry Authors: Fredrickson, R.T. Fredrickson, D.C. Tags: aperiodic crystals crystal structure prediction intermetallic phases research papers Source Type: research
Synthesis, crystal structure and phase transitions of novel hybrid perovskite: bis(1,2-diaminopropane) di- μ -chloro-bis[diaquadichloromanganate(II)] dichloride
Single crystals of bis(1,2-diaminepropane) di- μ -chloro-bis[diaquadichloromanganate(II)] dichloride have been prepared by evaporation from ethanoic solution. The triclinic X-ray crystal structure is built as layers of centrosymmetric dimers of [Mn(Cl)4(H2O)2]2 − octahedra and 1,2-diaminopropane. The inorganic part consists of Mn octahedra sharing one edge and distributed in the basal ac plane along the a direction. These doubly negative charged layers are separated along the b axis by a positively charged diamine propane layer. One Cl − anion contributes to the electroneutrality of the crystal interacting with both i...
Source: Acta Crystallographica Section B - July 6, 2023 Category: Chemistry Authors: Abdel-Aal, S.K. Souhassou, M. Durand, P. Lecomte, C. Abdel-Rahman, A.S. Claiser, N. Tags: lead-free hybrid perovskites crystal structure phase transitions difference scanning calorimetry research papers Source Type: research
Effect of La doping on the structure and cycloidal spin ordering in multiferroic BiFeO3
A series of Bi1 – xLaxFeO3 samples with 0.00 ≤ x ≤ 0.30 was synthesized by the sol – gel method. The effects of lanthanum concentration on the phase formation, microstructure and cycloidal spin ordering were studied using X-ray diffraction, scanning electron microscopy and M ö ssbauer spectroscopy. The crystal structure of the La-doped bismuth ferrite transformed from rhombohedral R3c (x ≤ 0.05) to a mixture of R3c and cubic Pm3m (0.07 ≤ x ≤ 0.15) and finally to a mixture of R3c, Pm3m and orthorhombic Pbam (0.20 ≤ x ≤ 0.30). The Pbam phase, with characteristic porous microstructure shown by microscopy im...
Source: Acta Crystallographica Section B - July 6, 2023 Category: Chemistry Authors: Pikula, T. Siedliska, K. Szumiata, T. Panek, R. Mitsiuk, V.I. Ruchomski, L. Jartych, E. Tags: bismuth ferrite spin cycloid X-ray diffraction ö ssbauer spectroscopy research papers Source Type: research
New data on the crystal chemistry of the natural two-layer aluminosilicates latiumite and tuscanite
The crystal chemistry of the natural microporous two-layer aluminosilicates (2D zeolites) latiumite and tuscanite is re-investigated based on new data on the chemical composition, crystal structures, and infrared and Raman spectra. The CO32 − -depleted and P- and H-enriched samples from Sacrofano paleovolcano, Lazio, Italy, are studied. Both minerals are monoclinic; latiumite P21, a = 12.0206 (3), b = 5.09502 (10), c = 10.8527 (3) Å , β = 107.010 (3) ° , V = 635.60 (3) Å 3 and tuscanite P21/a, a = 23.9846 (9), b = 5.09694 (15), c = 10.8504 (4) Å , β = 107.032 (4) ° ,...
Source: Acta Crystallographica Section B - July 4, 2023 Category: Chemistry Authors: Zubkova, N.V. Chukanov, N.V. Varlamov, D.A. Vigasina, M.F. Pekov, I.V. Ksenofontov, D.A. Pushcharovsky, D.Y. Tags: latiumite tuscanite double-layer aluminosilicate microporous silicate 2D zeolite research papers Source Type: research
Experimental charge density and topological analysis of tetraaquabis(hydrogenmaleato)nickel(II): a comparison with Hirshfeld atom refinement
Experimental charge density analysis is conducted on the coordination compound tetraaquabis(hydrogenmaleato)nickel(II), which exhibits a short intramolecular hydrogen bond. Through topological analysis, the nature of Ni — O bonds is concluded to be intermediate between ionic and covalent, but mainly presenting an ionic character, while the short hydrogen bond is classified as covalent in nature. The compound was also analysed after Hirshfeld atom refinement performed using NoSpherA2. A topological analysis was conducted on the molecular wavefunction and the results are compared with those obtained from experiment. In gen...
Source: Acta Crystallographica Section B - June 30, 2023 Category: Chemistry Authors: Pinto, C.B. Dos Santos, L.H.R. Rodrigues, B.L. Tags: hydrogen bond chemical bond quantum crystallography aspherical atom research papers Source Type: research
A fresh view on the structure and twinning of owyheeite, a rod-polytype and twofold superstructure
Owyheeite [Cu0.09 (1)Ag2.77 (4)Pb10.23 (4)Sb10.89 (5)S28.00 (5)] crystallizes as a twofold superstructure with P21/n symmetry and pseudo-orthorhombic metrics [a = 8.1882 (3) Å , b = 27.2641 (7) Å , c = 22.8679 (7) Å , β = 90.293 (3) ° , V = 5105.0 (3) Å 3, Z = 4]. Owyheeite is systematically twinned by reflection at (021) or equivalently (021). Twinning is explained by describing a simplified Pmcn archetype structure as polytype built of two kinds of rods, which contact via electron-pair micelles. A procedure of generating hypothetical polytypes by tiling space ...
Source: Acta Crystallographica Section B - June 23, 2023 Category: Chemistry Authors: St ö ger, B. G ö b, C. Topa, D. Tags: mineral superstructure polytypism twinning research papers Source Type: research
Structure of the new iron(II) oxalate potassium salt K2Fe[(C2O4)2(H2O)2] · 0.18H2O
The discovery of a new FeII oxalate framework of composition K2Fe[(C2O4)2(H2O)2] · 0.18H2O is reported. Its crystal structure was solved by means of single crystal and powder X-ray diffraction. The new organic – inorganic hybrid compound crystallizes in the orthorhombic space group Pca21 with unit-cell parameters: a = 12.0351 (4) Å , b = 15.1265 (5) Å , c = 10.5562 (4) Å . This crystal structure, containing eight chemical formula, consists of a succession of FeO4(H2O)2 octahedra and K+ cations growing along b direction. Magnetization measurements indicate that the title compound is paramagnetic over the i...
Source: Acta Crystallographica Section B - June 22, 2023 Category: Chemistry Authors: Amanchar, S. Schweitzer, T. Mazet, T. Malaman, B. Diop, L.V.B. Francois, M. Tags: metal – organic framework iron(II) oxalate crystal structure research papers Source Type: research
A new ternary derivative of the Laves phases in the Mg – Co – Ga system
Crystal structures of MgCoGa, Mg0.74CoGa0.52 and Mg0.49CoGa0.15 phases from the Mg – Co – Ga system were investigated using single-crystal diffraction. These structures belong to the family of so-called Laves phases. Hexagonal MgCoGa crystallizes as a disordered phase within the MgZn2 structure type. The orthorhombic structure of Mg0.74CoGa0.52 is a distortion variant of MgZn2 and URe2 structure type, and the structural relation is demonstrated in terms of a B ä rnighausen formalism group – subgroup transformation scheme. The structure of trigonal phase Mg0.49CoGa0.15 is strongly disordered, as is shown by the prese...
Source: Acta Crystallographica Section B - June 22, 2023 Category: Chemistry Authors: Pavlyuk, N. Dmytriv, G. Pavlyuk, V. Ciesielski, W. Rozdzynska-Kielbik, B. Indris, S. Ehrenberg, H. Tags: intermetallics Laves phases magnesium alloys single-crystal methods chemical bonding research papers Source Type: research
Unusual flash cooling-induced phase in a crystal of triphenylsilanol
The unique phase in a crystal of triphenylsilanol (Ph3SiOH) is reported. It is observed that after the crystal is flash-cooled from room temperature to 100 K, a new stable ordered phase II occurs with an increase in the unit-cell parameters compared to the earlier reported phase I. The new phase II occurs upon fast cooling while on slow cooling the disordered phase I is present. Gradual heating from 100 K (phase II) causes the crystal to return to the original phase I at about 150 K. The crystal undergoes the observed transformation in a reversible manner in many consecutive flash cooling/heating cycles without...
Source: Acta Crystallographica Section B - May 30, 2023 Category: Chemistry Authors: Krawczyk, M.K. Tags: triphenylsilanol flash cooling crystal structure research papers Source Type: research
Application of the method for visualization of noncovalent interactions in conformational polymorphs of four organic acids
A method for the visualization of noncovalent interactions using examples of the conformational polymorphs of four organic compounds: 2-(phenylamino)nicotinic, 2-(3-chloro-2-methylphenylamino)nicotinic, N-(3-chloro-2-methylphenyl)anthranilic and 2-(methylphenylamino)nicotinic acids is examined. The changes in noncovalent contacts are plotted against the angle between the planes of aromatic rings allowing a visual representation of conformational adjustment of molecules as well as packing features of crystal structures. According to the k – Φ criterion, the studied structures represent conformational polymorphs. Differen...
Source: Acta Crystallographica Section B - May 30, 2023 Category: Chemistry Authors: Pirozhkov, P.A. Uhanov, A.S. Savchenkov, A.V. Tags: polymorphism noncovalent interactions conformation packing Voronoi – Dirichlet polyhedron research papers Source Type: research
Proton tautomerism in 5-dimethylaminomethylidene-4-(o-,m-,p-hydroxyphenyl)amino-1,3-thiazol-2(5H)-ones: synthesis, crystal structure and spectroscopic studies
Three new 5-dimethylaminomethylidene-4-phenylamino-1,3-thiazol-2(5H)-ones with an hydroxyl group in the ortho-, meta- and para- positions on the phenyl ring were synthesized in order to deduce the structural changes occurring on prototropic tautomerism of the amidine system. The existence of all the title compounds solely in the amino tautomeric form has been established in the solid and liquid (dimethyl sulfoxide solution) phases. The title compounds are analyzed from the point of view of the electronic effects and conformational freedom of their molecules. The intermolecular interactions in the crystals and their supramo...
Source: Acta Crystallographica Section B - May 16, 2023 Category: Chemistry Authors: Pyrih, A. Ł api ń ski, A. Zi ę ba, S. Mizera, A. Lesyk, R. Jaskolski, M. Gzella, A.K. Tags: 4-amino-thiazolin-2-ones proton tautomerism X-ray analysis spectroscopic analysis DFT QTAiM Hirshfeld surfaces. research papers Source Type: research
Synthesis and structure of two novel trans-platinum complexes
Here for the first time the synthesis and characterization of two new trans-platinum complexes, trans-[PtCl2{HN=C(OH)C6H5}2] (compound 1) and trans-[PtCl4(NH3){HN=C(OH)tBu}] (compound 2) [with tBu = C(CH33] are described. The structures have been characterized using nuclear magnetic resonance spectroscopy and X-ray single-crystal diffraction. In compound 1 the platinum cation, at the inversion center, is in the expected square-planar coordination geometry. It is coordinated to two chloride anions, trans to each other, and two nitrogen atoms from the benzamide ligands. The van der Waals interactions between the molecules pr...
Source: Acta Crystallographica Section B - May 5, 2023 Category: Chemistry Authors: Vinci, D. Chateigner, D. Tags: platinum complexes synthesis anticancer drugs X-ray diffraction crystal structure research papers Source Type: research
Arsenic(III) oxide intercalate with ammonium chloride: crystal structure revision and thermal characterization
According to the crystal structure determination by Edstrand& Blomqvist [Ark. Kemi (1955), 8, 245 – 256], intercalate NH4Cl · As2O3 · 0.5H2O ({\bf Y_{{NH}_{4}Cl}}) is not isostructural with compound KCl · As2O3 · 0.5H2O. This is very unlikely because both NH4Br · 2As2O3 and KBr · 2As2O3 as well as NH4I · 2As2O3 and KI · 2As2O3 are isostructural. Hence, intercalate {\bf Y_{{NH}_{4}Cl}} has been studied using single-crystal X-ray diffraction in addition to attenuated total reflection Fourier transform infrared (ATR-FTIR) and 15N solid-state magic-angle spinning nuclear magnetic resonance (ssNMR) spectroscopies. The...
Source: Acta Crystallographica Section B - April 18, 2023 Category: Chemistry Authors: Wrze ś niewska, W. Paluch, P. Gu ń ka, P.A. Tags: arsenic(III) oxide intercalates solid-state NMR crystal structure research papers Source Type: research
The study of mineral behavior at low and high temperatures and their properties using a combination of different methods has not become routine yet
(Source: Acta Crystallographica Section B)
Source: Acta Crystallographica Section B - April 18, 2023 Category: Chemistry Authors: Aksenov, S.M. Tags: crystal structure azoproite oxoborate ludwigite group oxidation thermal expansion scientific commentaries Source Type: research
A topological approach to reconstructive solid-state transformations and its application for generation of new carbon allotropes
A novel approach is proposed for the description of possible reconstructive solid-state transformations, which is based on the analysis of topological properties of atomic periodic nets and relations between their subnets and supernets. The concept of a region of solid-state reaction that is the free space confined by a tile of the net tiling is introduced. These regions (tiles) form the reaction zone around a given atom A thus unambiguously determining the neighboring atoms that can interact with A during the transformation. The reaction zone is independent of the geometry of the crystal structure and is determined only b...
Source: Acta Crystallographica Section B - April 5, 2023 Category: Chemistry Authors: Kabanov, A.A. Bukhteeva, E.O. Blatov, V.A. Tags: topological approach solid-state transformations tilings carbon allotropes research papers Source Type: research
