Search results for "Crystal system"
showing 10 items of 13557 documents
Cation Environment in BaCeO3-Based Protonic Conductors: a Computational Study
2009
Geometry calculations were performed on pure BaCeO(3) fragments and on Y- and In-doped derivatives. HF and DFT approaches were used to investigate monoclinic and orthorhombic structures. The computational methods, structural models, and electronic structure investigation protocols were tuned taking into consideration and balancing the consistency of the results against the computational cost. The calculated structures and energetics parameter, as well as the detailed orbital analysis performed on the corresponding BaCeO(3) derivatives allowed us to explain experimental findings and to develop a procedure to study the cationic octahedral environment of doped X:BaCeO(3) (X = Y, In) and undope…
Unique Bridging Function of the Triazole Core in Copper(II) Chloride Complexes with 1-Allylbenzotriazole
2005
During alternating-current electrochemical synthesis of copper(I) π-complex of [CuCl{C6H4N3(C3H5)}] composition, starting from ethanol solution, containing CuCl2·2H2O and 1-allylbenzotriazole, green crystals of intermediate [CuII3Cl6{C6H4N3(C3H5)}4] (I) compound has been obtained upon 24 h. After some days these crystals transform into red ones of [CuII2Cl4{C6H4N3(C3H5)}3] (II). Both compounds were X-Ray structurally investigated. Crystals of I are triclinic, sp.gr. a = 9.1329(9), b = 10.0352(4), c = 12.239(3) A, α = 76.443(13), β = 84.470(14), γ = 76.808(7)°, V = 1060.5(3) A3, R = 0.0414 for 3311 reflections. II: monoclinic, C2/c, a = 13.828(1), b = 15.044(2), c = 10.702(1) A, β = 91.36(1)…
CCDC 1564495: Experimental Crystal Structure Determination
2017
Related Article: Fernando Rabasa-Alcañiz, Javier Torres, María Sánchez-Roselló, Tomás Tejero, Pedro Merino, Santos Fustero, Carlos del Pozo|2017|Adv.Synth.Catal.|359|3752|doi:10.1002/adsc.201700975
Facile synthesis of 5β-cholane-sym-triazine conjugates starting from metformin and bile acid methyl esters: Liquid and solid state NMR characterizati…
2009
Abstract Four bile acid-triazine conjugates: N2′,N2′-dimethyl-6′-(3α-hydroxy-5β-24-norcholyl)-1′,3′,5′-triazine-2′,4′-diamine (lithocholyl triazine, 4a), N2′,N2′-dimethyl-6′-(3α,7α-dihydroxy-5β-24-norcholyl)-1′,3′,5′-triazine-2′,4′-diamine (chenodeoxycholyl triazine, 4b), N2′,N2′-dimethyl-6′6′-(3α,12α-dihydroxy-5β-24-norcholyl)-1′,3′,5′-triazine-2′,4′-diamine (deoxycholyl triazine) (4c), and N2′,N2′-dimethyl-6′-(3α,7α,12α-trihydroxy-5β-24-norcholyl)-1′,3′,5′-triazine-2′,4′-diamine (cholyl triazine) (4d) have been prepared and characterized by liquid and solid state NMR. An improved synthetic method produced better yields and an easier purification procedure for 4d than reported in the liter…
Photoluminescent and Slow Magnetic Relaxation Studies on Lanthanide(III)-2,5-pyrazinedicarboxylate Frameworks
2017
In the series described in this work, the hydrothermal synthesis led to oxidation of the 5-methyl-pyrazinecarboxylate anion to the 2,5-pyrazinedicarboxylate dianion (2,5-pzdc) allowing the preparation of three-dimensional (3D) lanthanide(III) organic frameworks of formula {[Ln2(2,5-pzdc)3(H2O)4]·6H2O}n [Ln = Ce (1), Pr (2), Nd (3), and Eu (4)] and {[Er2(2,5-pzdc)3(H2O)4]·5H2O}n (5). Single-crystal X-ray diffraction on 1–5 reveals that they crystallize in the triclinic system, P1 space group with the series 1–4 being isostructural. The crystal structure of the five compounds are 3D with the lanthanide(III) ions linked through 2,5-pzdc2– dianions acting as two- and fourfold connectors, buildi…
Variable-temperature X-ray crystal structure determinations of {Fe[tren(6-Mepy)3]}(ClO4)2and {Zn[tren(6-Mepy)3]}(ClO4)2compounds: correlation of the …
2007
Variable-temperature X-ray crystal structure determinations (80–330 K) on compounds {Fe[tren(6-Mepy)3]}(ClO4)2(1-Fe) {tren(6-Mepy)3is tris[3-aza-4-(6-methyl-2-pyridyl)but-3-enyl]amine} and {Zn[tren(6-Mepy)3]}(ClO4)2(1-Zn) {tren(6-Mepy)3is tris[3-aza-4-(6-methyl-2-pyridyl)but-3-enyl]amine} were carried out together with a detailed analysis of the unit-cell volume and parameters in the spin transition region for (1-Fe). Both compounds crystallize in the monoclinic system and retained the space groupP21/cat all measured temperatures. The Fe and Zn atoms are surrounded by six N atoms belonging to imine groups and pyridine groups of the trifurcated ligand, adopting a pseudo-octahedral symmetry. …
Synthesis, crystal structure and magnetic properties of the complex [ReCl3(tppz)]·MeCN
2015
The reaction of the starting materials [ReIIICl3(MeCN)(PPh3)2] or [ReVOCl3(PPh3)2] with 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz) in acetonitrile yielded the Re(III) complex [ReCl3(tppz)]·MeCN (1). This complex crystallizes in the monoclinic space group P21/n and its crystal structure consists of neutral mononuclear entities with meridional geometry of the chloride ligands, and the six-coordination of the Re(III) ion being completed by the tridentate tppz ligand. Each metal centre exhibits a highly distorted octahedral coordination with Re–Cl and Re–Ntppz bond lengths covering the ranges 2.3590(9)–2.3606(8) and 1.971(2)–2.096(2) A, respectively. The magnetic properties of 1 have been inves…
Preparation, crystal structure at 298 and 90 K and phase transition in (C2H5NH3)2 [SbBr5] studied by the single crystal X-ray diffraction method
2004
The reaction of antimony(III) oxide with ethylamine, in molar ratios from 1:1 to 1:10, in concentrated hydrobromic acid leads to the formation of one product - bis(ethylammonium) pentabromoantimonate( III). The structure of (C2H5NH3)2[SbBr5] was determined at 298 and 90 K, below and above the phase transition that occurs at about 158.5 K. The orthorhombic system was found in both phases, space groups Cmca and Pbca at 298 and 90 K, respectively. At both temperatures the structure consists of [SbBr6]3− octahedra connected via cis bromine atoms forming one-dimensional zig-zag [{SbBr5}2−]n chains. The ethylammonium cations fill the space between polyanionic chains. The organic and inorganic sub…
Phonon calculations in cubic and tetragonal phases of SrTiO3: A comparative LCAO and plane-wave study
2011
The atomic, electronic structure and phonon frequencies have been calculated in cubic and low-temperature tetragonal SrTiO${}_{3}$ phases at the ab initio level. We demonstrate that the use of the hybrid exchange-correlation PBE0 functional gives the best agreement with experimental data. The results for the standard generalized gradient approximation (PBE) and hybrid PBE0 functionals are compared for the two types of approaches: a linear combination of atomic orbitals (CRYSTAL09 computer code) and plane waves (VASP5.2 code). The relation between cubic and tetragonal phases and the relevant antiferrodistortive phase transition is discussed in terms of group theory and is illustrated with an…
CCDC 190421: Experimental Crystal Structure Determination
2003
Related Article: D.Gudat, B.Lewall, M.Nieger, I.Detmer, L.Szarvas, P.Saarenketo, G.Marconi|2003|Chem.-Eur.J.|9|661|doi:10.1002/chem.200390074