scholarly journals Polymorphs and derivates of Sr2LiAlO4:Eu2+

2019 ◽  
Vol 74 (10) ◽  
pp. 765-772
Author(s):  
Gregor J. Hoerder ◽  
Simon Peschke ◽  
Klaus Wurst ◽  
Markus Seibald ◽  
Dominik Baumann ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Layered Structure ◽  
Partial Substitution ◽  
Monoclinic Space Group ◽  
Structure Property ◽  
Orthorhombic Space Group ◽  
Quaternary Compound ◽  
Space Group ◽  
Structure Property Relationships ◽  
Luminescence Performance

AbstractRecently, Wang et al. (Z. Wang, J. Ha, Y. H. Kim, W. B. Im, J. McKittrick, S. P. Ong, Joule2018, 2, 914–926) predicted and discovered Sr2LiAlO4, a quaternary compound with a layered structure crystallizing in the monoclinic space group P21/m, and they refined the structure from PXRD data. Upon partially substituting strontium with europium, the substance exhibits a yellow broadband luminescence consisting of two overlapping emission bands. In this paper, the crystal structure of Sr2LiAlO4 is confirmed by additional SC-XRD measurements and a newly discovered polymorph of Sr2LiAlO4 is presented crystallizing in the orthorhombic space group Cmcm. When Eu2+ is incorporated, this polymorph exhibits only one of the emission bands present in the P21/m-polymorph. Additionally, two substitutional variants of Sr2LiAlO4 are presented along with their luminescence properties upon incorporating Eu2+. One with a partial substitution of strontium for barium, leading to a structure in space group Pnma, and one with a partial substitution of oxygen for nitrogen, exhibiting the structure in space group Cmcm. The structure-property relationships in the above mentioned compounds are discussed with regard to their luminescence performance.

Two lithium tricyanomethanide compounds: syntheses and single-crystal structure determination of LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO

2015 ◽  
Vol 70 (3) ◽  
pp. 191-196 ◽  
Author(s):  
Olaf Reckeweg ◽  
Francis J. DiSalvo
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Structure Determination ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Cell Parameters ◽  
New Compounds

AbstractThe new compounds LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO were synthesized and their crystal structures were determined. Li[C(CN)3]·½ (H3C)2CO crystallizes in the orthorhombic space group Ima2 (no. 46) with the cell parameters a=794.97(14), b=1165.1(2) and c=1485.4(3) pm, while LiK[C(CN)3]2 adopts the monoclinic space group P21/c (no. 14) with the cell parameters a=1265.7(2), b=1068.0(2) and c=778.36(12) pm and the angle β=95.775(7)°. Single crystals of K[C(CN)3] were also acquired, and the crystal structure was refined more precisely than before corroborating earlier results.

79Br, 127I NQR of Diammoniumalkyl Halides and Piperazinium Halides. Crystal Structure of Piperazinium Dibromide Monohydrate and Piperazinium Monoiodide

1989 ◽  
Vol 44 (1) ◽  
pp. 41-55 ◽  
Author(s):  
Jutta Hartmann ◽  
Shi-Qi Dou ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Temperature Range

Abstract The 79Br and 127I NQR spectra were investigated for 1,2-diammoniumethane dibromide, -diiodide, 1,3-diammoniumpropane dibromide, -diiodide, piperazinium dibromide monohydrate, and piperazinium monoiodide in the temperature range 77 ≦ T/K ≦ 420. Phase transitions could be observed for the three iodides. The temperatures for the phase transitions are: 400 K and 404 K for 1,2-diammoniumethane diiodide, 366 K for 1,3-diammoniumpropane diiodide, and 196 K for piperazinium monoiodide.The crystal structures were determined for the piperazinium compounds. Piperazinium dibromide monohydrate crystallizes monoclinic, space group C2/c, with a= 1148.7 pm, 0 = 590.5 pm, c= 1501.6pm, β = 118.18°, and Z = 4. For piperazinium monoiodide the orthorhombic space group Pmn 21 was found with a = 958.1 pm, b = 776.9 pm, c = 989.3 pm, Z = 4. Hydrogen bonds N - H ... X with X = Br, I were compared with literature data.

Untersuchungen an Polyhalogeniden, XXXVI. Zur Kenntnis des Oktaiodid-Ions I82-: Darstellung und Kristallstruktur des [(Crypt-2.2.2)H2]l8, des [Ni(phen)3]I8 · 2CHCl3 und der Bis(N-alkylurotropinium) oktaiodide (UrR)2I8 mit R = Methyl und Ethyl / Studies on Polyhalides, XXXVI. On the Octaiodide Ion I82-: Preparation and Crystal Structure of [(Crypt-2.2.2)H2]I8, of [Ni(phen)3]I8-2CHCl3 and of the Bis(N-alkylurotropinium)octaiodides (UrR)2I8 with R = methyl and ethyl

1998 ◽  
Vol 53 (7) ◽  
pp. 641-652 ◽  
Author(s):  
Arista Gräfe-Kavoosian ◽  
Shida Nafepour ◽  
Klaus Nagel ◽  
Karl-Friedrich Tebbe
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Iodine Molecule ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group

Abstract The new compound [(Crypt-2.2.2)H2]I8 has been prepared by the reaction of [(Crypt-2.2.2)H2](I3)2 with iodine in methanol. It crystallizes in the orthorhombic space group Pbcn with a = 11.476 (2), b = 13.589 (2), c = 22.888 (2) Å and Z = 4. The crystal structure has been refined to RF = 0.031 for 1618 reflections. It may be described as a layerlike packing of octaiodide anions I82-and diprotonated 2.2.2-Crypt as cations. The non planar octaiodide anion is built up from two triiodide groups and a bridging iodine molecule.Tris(1, 10-phenanthroline)nickel(II) octaiodide bis(chloroform) crystallizes in the monoclinic space group P21/n with a = 11.683 (8), b = 21.717 (8), c = 20.752 (5) Å, β = 95.03 (5)° and Z = 4 formula units. The crystal structure has been refined to RF = 0.058 for 3894 reflections. The structure consists of two chloroform molecules, octahedrally coordinated complex cations [Ni(phen)3]2+ and nonplanar octaiodide anions I82- each composed of two asymmetric triiodide units I3- weakly associated with an elongated bridging iodine molecule I2.The already known structure of bis(N-methylurotropinium) octaiodide, (UrMe)2I8, has been verified and more accurate crystal data have been collected. The crystal structure has been refined to RF = 0.045 for 1908 reflections. The compound crystallizes in the monoclinic space group P21/c with a = 11.302 (2), b = 9.850 (2), c = 14.188 (2) Å , β = 92.59 (1)° and Z = 2. The anion has the shape of a stretched Z.The structure of bis(N-ethylurotropinium) octaiodide (UrEt)2I8 has been determined and a new configuration (I3-, I5-) for octaiodide ions between Z (I3- · I2 ·I3-) and a “broken” configuration (I3-, I5-) has been observed. The compound crystallizes in the triclinic space group P1̄ with a = 9.741 (3), b = 11.815 (3), c = 15.426 (3) Å, α = 91.80 (2), β = 107.14 (2), γ = 90.04 (2)° and Z = 2. The crystal structure has been refined to RF = 0.037 for 3657 reflections.

Untersuchungen an Polyhalogeniden, XXI [1] Die Ethyltriphenylphosphonium-Polyiodide EtPh3PIn mit n = 3,5 und 7 / Studies of Polyhalides, XXI [1] Ethyltriphenylphosphonium Polyiodides EtPh3PIn with n = 3,5 and 7

1995 ◽  
Vol 50 (11) ◽  
pp. 1685-1691 ◽  
Author(s):  
Karl-Friedrich Tebbe ◽  
Taraneh Farida
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Stoichiometric Reaction

The compounds EtPh3PI3, EtPh3PI5 and EtPh3PI7 have been prepared by the stoichiometric reaction of EtPh3PI with iodine in a mixture of dichloromethane and ethanol. EtPh3PI3 cry­stallizes in the monoclinic space group P21/n with a = 1176.7(3) pm, b = 1202.5(3) pm, c = 1565.9(4) pm, β=93.22(2)° and Z = 4. The crystal structure has been refined to RF = 0.043 for 3394 reflections. EtPh3PI5 crystallizes in the monoclinic space group I2/a with a = 1913.9(4) pm, b = 1239.0(2)pm, c = 2435.1(4) pm, β = 115.84(1)° and Z = 8. The crystal structure has been refined to RF =0.052 for 3043 reflections. EtPh3PI7 crystallizes in the orthorhombic space group Pbca with a = 1702.7(4)pm. b = 1952.5(4) pm, c = 1809.8(4) pm und Z = 8. The crystal structure has been refined to RF = 0.053 for 3208 reflections. The structures may be described as layerlike packings of cations Ph3EtP+ and of anions I-3, I-5 and I-7, respectively. The isolated triiodide ion I-3 is slightly asymmetrical and slightly bent as expected. The pentaiodide ion I-5 forms iodine ribbons like a rope ladder. The heptaiodide ion I-7 is composed of pentaiodide groups and iodine molecules connected to puckered anionic layers.

Struktur und X-X-Elektronendichteverteilung in Diaminoboranen des Typs (RCH3N)2BCH3 mit R = H, CH3

1991 ◽  
Vol 46 (1) ◽  
pp. 84-96 ◽  
Author(s):  
Norbert Niederprüm ◽  
Roland Boese ◽  
Günter Schmid
Keyword(s):  
Crystal Structure ◽  
Electron Density ◽  
Zone Melting ◽  
Infrared Light ◽  
Monoclinic Space Group ◽  
Difference Electron Density ◽  
Orthorhombic Space Group ◽  
Torsion Angles ◽  
Space Group ◽  
The Mean

Using a miniature zone melting device with focused infrared light it was possible to grow crystals of bis(dimethylamino)methylborane (1) and bis(monomethylamino)methylborane (2) at temperatures o f 182 K and 177 K, respectively. The crystal structure and the X - X difference electron density have been determined at temperatures o f 120 K (1) and 115 K (2).1 crystallizes in the orthorhombic space group Pbca with a = 758.87(7), b = 1559.74(12) and c = 1296.73(12) pm. The mean B - N distance is 143.1(3) pm.2 crystallizes in the monoclinic space group P21/c with a = 775.06(6), b = 1533.94(17), c = 1011.06(10) pm and β = 102.669(7)° with intermolecular N ··· H hydrogen bridges. The mean B - N distance is 141.5(2) pm.It is shown that the variation of torsion angles at small angles has more influence on bond lengths than the same or a greater variation at large angles and that it is necessary to pay more attention to the torsion angles ( C - B - N - C ) rather than to the interplanar angles (plane N ,B,N - plane N ,C,C ).

scholarly journals A variable-temperature study of a phase transition in barbituric acid dihydrate

2005 ◽  
Vol 61 (4) ◽  
pp. 464-472 ◽  
Author(s):  
Gary S. Nichol ◽  
William Clegg
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Barbituric Acid ◽  
Crystal Packing ◽  
Variable Temperature ◽  
Mirror Plane ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Acta Cryst ◽  
Space Group

The crystal structure of barbituric acid dihydrate (C4H4N2O3·2H2O) has twice been reported as orthorhombic, space group Pnma, with all atoms (except for CH2 H atoms) lying on the mirror plane [Al-Karaghouli et al. (1977). Acta Cryst. B33, 1655–1660; Jeffrey et al. (1961). Acta Cryst. 14, 881–887]. The present study has found that at low temperatures, below 200 K, the crystal structure is no longer orthorhombic but is non-merohedrally twinned monoclinic, space group P21/n. This phase is stable down to 100 K. Above 220 K the crystal structure is orthorhombic, and between 200 and 220 K the structure undergoes a phase change, with the monoclinic-to-orthorhombic phase transition itself taking place at around 216–217 K. The size of the β angle in the monoclinic structure is temperature dependent; at 100 K β is around 94° and it decreases in magnitude towards 90° as the temperature increases. Although the hydrogen-bonding motifs are the same for both crystal systems, there are significant differences in the crystal packing, in particular the out-of-plane displacement of the two water molecules and the sp 3-hybridized C atom of barbituric acid.

Mono- and difunctional furan-based 1,2,3,5-dithiadiazolyl radicals; preparation and solid state structures of 2,5-[(S2N2C)OC4H2(CN2S2)] and 2,5-[(S2N2C)OC4H2(CN)]

1992 ◽  
Vol 70 (3) ◽  
pp. 919-925 ◽  
Author(s):  
A. Wallace Cordes ◽  
Charles M. Chamchoumis ◽  
Robin G. Hicks ◽  
Richard T. Oakley ◽  
Kelly M. Young ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
The Mean ◽  
Solid State Structures ◽  
Solid State Characterization

The preparation and solid state characterization of the bifunctional radical furan-2,5-bis(1,2,3,5-dithiadiazolyl) 2,5-[(S2N2C)OC4H2(CN2S2)] and the related monofunctional radical 2-cyanofuran-5-(1,2,3,5-dithiadiazolyl) 2,5-[(S2N2C)OC4H2(CN)] are described. The crystal structure of 2,5-[(S2N2C)OC4H2(CN2S2)] is orthorhombic, space group Pna21, and consists of interleaved arrays of dimers, for which the mean interannular [Formula: see text] contact is 3.137 Å. The crystal structure of the monofunctional radical 2,5-[(S2N2C)OC4H2(CN)] is monoclinic, space group P21/n, and consists of a ribbon-like network of dimers (mean interannular [Formula: see text] interconnected by close head-to-tail [Formula: see text] contacts. The dimer units form stacks parallel to z, with a mean interdimer [Formula: see text] separation of 3.956 Å. The similarities and differences between these two crystal structures and those of related benzene-substituted systems are discussed. Keywords: dithiadiazolyl radicals, furan-based diradicals, cyanofuran-based radicals, radical dimers, crystal structures.

The crystal structure of Cu2GeSe3 and the structure-types of the I2-IV-VI3 family of semiconducting compounds

2021 ◽  
Vol 77 (1) ◽  
pp. 158-167
Author(s):  
Analio Dugarte-Dugarte ◽  
Nahum Ramírez Pineda ◽  
Luis Nieves ◽  
José Antonio Henao ◽  
Graciela Díaz de Delgado ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Unit Cell Parameters ◽  
Orthorhombic Space Group ◽  
Initial Report ◽  
Space Group ◽  
Cell Parameters ◽  
Semiconducting Compounds ◽  
Bond Valence Model

Almost 50 years after the initial report, the crystal structure of Cu2GeSe3, a I2-IV-VI3 semiconductor, has been revised using modern single-crystal X-ray diffraction data. The structure of this material can be properly described in the monoclinic space group Cc (No. 9) with unit-cell parameters a = 6.7703 (4) Å, b = 11.8624 (5) Å, c = 6.7705 (4) Å, β = 108.512 (6)°, V = 515.62 (5) Å3, Z = 4, rather than in the orthorhombic space group Imm2 (No. 44) with unit-cell parameters a = 11.860 (3), b = 3.960 (1), c = 5.485 (2) Å, V = 257.61 Å3, Z = 2, as originally proposed [Parthé & Garín (1971). Monatsh. Chem. 102, 1197–1208]. Contrary to what was observed in the orthorhombic structure, the distortions of the tetrahedra in the monoclinic structure are consistent with the distortions expected from considerations derived from the bond valence model. A brief revision of the structures reported for the I2-IV-VI3 family of semiconducting compounds (I: Cu, Ag; IV: Si, Ge, Sn; and VI: S, Se, Te) is also presented.

scholarly journals Structural Characterization of Two Polymorphs of 1-(4-Methylpyridin-2-yl)thiourea and Two Derived 2-Aminothiazoles

2020 ◽  
Author(s):  
Denise Böck ◽  
Andreas Beuchel ◽  
Richard Goddard ◽  
Peter Imming ◽  
Rüdiger W. Seidel
Keyword(s):  
Crystal Structure ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Hantzsch Reaction ◽  
Orthorhombic Space Group ◽  
Monoclinic System ◽  
Space Group ◽  
Crystal And Molecular Structures ◽  
Polymorphic Forms ◽  
Hydrogen Bonded

Abstract Two polymorphic forms of 1-(4-methylpyridin-2-yl)thiourea (1) and the crystal and molecular structures of the 2-aminothiazoles N-(4-methylpyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (2) and N-(4-methylpyridin-2-yl)-4-(pyrazin-2-yl)thiazol-2-amine (3), derived from 1 and the respective α-bromoketone via the Hantzsch reaction, are described. Both polymorphic forms 1α (space group P21/c, Z = 4) and 1β (space group P21/n, Z = 8) crystallize in the monoclinic system but exhibit distinctly different intermolecular hydrogen bonding patterns. Compound 2 (orthorhombic, space group Pca21, Z = 8) forms polymeric N–H⋯N hydrogen-bonded zigzag tapes in the polar crystal structure, with a significant twisting between the thiazole and pyridine rings. In contrast, the crystal structure of 3 (monoclinic, space group P21/c, Z = 4) features nearly planar centrosymmetric N–H⋯N hydrogen-bonded dimers, which are laterally joined through long C–H⋯N contacts, affording a π⋯π stacked layered structure. Graphic Abstract Two polymorphs of 1-(4-methylpyridin-2-yl)thiourea and the crystal and molecular structures of two 2-aminothiazoles, derived from 1-(4-methylpyridin-2-yl)thiourea and α-bromoketones via Hantzsch reaction, are reported.

Organoamido- and Aryloxo-lanthanoids. IX. Preparations and Structures of Tris(η2-3,5-diphenyl-pyrazolato)lanthanoid(III) Complexes With Triphenylphosphine Oxide and Tetrahydrofuran

1993 ◽  
Vol 46 (12) ◽  
pp. 1881 ◽  
Author(s):  
JE Cosgriff ◽  
GB Deacon ◽  
BM Gatehouse
Keyword(s):  
Crystal Structure ◽  
Triphenylphosphine Oxide ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Oxygen Donor ◽  
Neodymium Complex ◽  
Cell Data

From reaction of lanthanoid metals with bis ( pentafluorophenyl )mercury and 3,5-diphenylpyrazole (HPh2pz) in 1,2-dimethoxyethane ( dme ) and treatment of the products with triphenylphosphine oxide, the complexes [ Ln (η2-Ph2pz)3(OPPh3)2].( dme )n ( Ln = Er or Nd , n = 1; Ln = La, n = 0.6) have been isolated. An X-ray crystal structure shows that the erbium complex [monoclinic, space group C2, a 22.08(3), b 14.30(1), c 13.37(1) Ǻ, β 124.09(7)°, Z 2 2730 'observed' data refined to R 0.046] is monomeric , with eight coordination of the metal. There is a trigonal bipyramidal arrangement of the centre ( Cen ) of the N-N bonds of three η2-3,5-diphenylpyrazolate groups ( ΣCen-Er-Cen 360°; ( Er -N) 2.344 Ǻ) and the oxygens of two equivalent trans triphenylphosphine oxide ligands [O- Er -O 176(1)°; Er -O 2.207(9)Ǻ]. Unit cell data indicate that the neodymium analogue [monoclinic, space group C2, a 23.01(3), b 14.94(2), c 13.82(2) Ǻ, β 123.65(8)°] is isostructural with the erbium complex. An analogous reaction of lanthanum or neodymium metal, Hg(C6F5)2, and HPh2pz in tetrahydrofuran ( thf ) gives [ Ln (η2-Ph2pz)3( thf )3]. thf ( Ln = La or Nd ). The X-ray crystal structure of the neodymium complex [orthorhombic, space group P212121, a 14.009(9), b 16.280(8), c 22.640(16)Ǻ, Z 4, 2967 'observed' data refined to R 0.046 reveals a nine-coordinate monomer with three η2-Ph2pz ligands [ Nd -N 2.420(10)-2.524(8)Ǻ] and three thf ligands [ Nd -O 2.497(8)-2.587(8)Ǻ]. There is a trigonal prismatic arrangement of the centres of the N-N bonds and the oxygen donor atoms.

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