scholarly journals Isolated versus Condensed Anion Structure V: X-ray Structure Analysis and 81Br NQR of t-butylammonium tribromocadmate(II)-1/2 water, i-propylammonium tribromocadmate(II), and tris-trimethylammonium heptabromodicadmate(II)

1999 ◽  
Vol 54 (10-11) ◽  
pp. 628-636 ◽  
Author(s):  
Hideta Ishihara ◽  
Keizo Horiuchi ◽  
Shi-qi Dou ◽  
Thorsten M. Gesing ◽  
J.-Christian Buhl ◽  
...  
Keyword(s):  
Phase Transition ◽  
Temperature Dependence ◽  
Crystal Structures ◽  
Structure Analysis ◽  
X Ray ◽  
81Br Nqr ◽  
The One ◽  
Acta Crystallogr

The crystal structures of the condensed bromocadmate anions with chains built of [CdBr3]∞ were de-termined by X-ray structure analysis at 300 K. In addition, the temperature dependence of the 81Br NQR frequencies was observed. [(t-C4H9NH3)CdBr3]2-H2O (1) tallizes with a double Br bridged chain (monoclinic, P2/c, Z = 4, a = 1963.4(8), b 87.7(4), c 1432.1(6) pm, and ß= 110.66(2)°). Six 81Br NQR lines are observed at temperatures between 77 and 330 K. (i-C3H7NH-3)CdBr3 (2) crystalliz-es with a triple Br bridged chain (orthrhombic, Pbca, Z= 8, a = 1975.4(6), b = 1415.8(4), c = 690.1(2) pm). (2) shows three 81Br NQR lines at temperatures between 77 and 193 K. A phase transition occurs at 224 K. The structure of [(CH3)3 NH]3Cd2Br7] (3) was redetermined. (3) consists of a triple Br bridged chain and a discrete [CdBr4] tetrahedron (hexagonal, P63mc, Z= 8, a = 1483.5(2), c = 685.7(5) pm). The structure of (3) is identical to the one reported by Daoud, Perret, and Dusausoy, Acta Crystallogr., B35, 2718 (1979). Three 81Br NQR lines are observed at temperatures between 77 and 243 K.

scholarly journals Crystal Structure and Dielectric Property of Endohedral Lithium Fullerene

2014 ◽  
Vol 70 (a1) ◽  
pp. C195-C195
Author(s):  
Shinobu Aoyagi ◽  
Kunihisa Sugimoto ◽  
Hiroshi Okada ◽  
Norihisa Hoshino ◽  
Tomoyuki Akutagawa
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Dielectric Property ◽  
Low Temperature ◽  
Dielectric Permittivity ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Structure Analysis ◽  
X Ray ◽  
Dielectric Phase

Endohedral lithium fullerene Li+@C60 can have a dielectric polarization by the off-centered location of the Li+ cation inside the C60 cage. The x-ray structure analysis of the PF6– salt [Li@C60](PF6) revealed that the Li+ cation occupies two off-centered equivalent positions at 20 K and hence the crystal is non-polar [1]. The disordered structure at low temperature is explained by a static orientation disorder of polar Li+@C60 cations and/or a dynamic tunneling of the Li+ cation inside the C60 cage. The Li+ tunneling would be suppressed by an intermolecular interaction at lower temperature and a dielectric phase transition might be induced. We reveal the dielectric property and crystal structure of [Li@C60](PF6) below 20 K in this study. The temperature dependence of the dielectric permittivity was measured for the single crystal down to 9 K. The dielectric permittivity increases with decreasing temperature according to the Curie-Weiss law. Such a behavior was also observed in H2O@C60 crystal but not in empty C60 crystal [2]. No dielectric phase transition was observed in H2O@C60 down to 8 K. In contrast, a dielectric anomaly suggesting a phase transition was observed in [Li@C60](PF6) around 18 K. The single-crystal x-ray diffraction experiment below 20 K was also performed at SPring-8 BL02B1. The crystal has a cubic structure at 20 K [1]. The temperature dependence of the cubic lattice constant shows no anomaly around 18 K. However, diffraction peaks that are forbidden for the given structure appear below 18 K. Thus the crystal symmetry is lowered by the dielectric phase transition. We present the result of the crystal structure analysis of the newly discovered low-temperature phase.

Zur Struktur und Dotierung von Selenosilikaten: die Kristallstruktur von Er2SeSiO4 und Er3,75Ca0,25Se2,75Cl0,25Si2O7 Structure and Doping of Seleno Silicates: the Crystal Structures of Er2SeSiO4 and Er3,75Ca0,25Se2,75Cl0,25Si2O7

1994 ◽  
Vol 49 (6) ◽  
pp. 733-740 ◽  
Author(s):  
Klaus Stöwe
Keyword(s):  
Crystal Structures ◽  
Structure Analysis ◽  
Rare Earths ◽  
Structure Determination ◽  
Lattice Parameters ◽  
Energy Dispersive ◽  
Space Group ◽  
X Ray ◽  
By Products

Well-shaped brown and pink isometric crystals were obtained as by-products of the synthesis of erbium selenides from the elements in evacuated and sealed silica ampoules with graphite inlets. They could be identified as erbium seleno mono- and disilicates by energy dispersive X-ray fluorescence and X-ray structure determination. The monosilicate Er2SeSiO4 crystallizes isotypically to Nd2SeSiO4 in the space group Pbcm with the lattice parameters a = 600.2(2), b = 688.0(2), c = 1075.2(2) pm and represents the second known seleno inosilicate of the rare earths. From X-ray structure analysis an isotypic relation between the disilicate Er3,75Ca0,25Se2,75Cl0,25Si2O7 and the compound Sm4S3Si2O7 was found, the former crystallizing in the space group I41/amd with the lattice parameters a - 1177.7(2) and c = 1376.5(2) pm. The doping o f the sorosilicate with the elements Ca and Cl originated from contam inations in the graphit inlets used in the procedure

scholarly journals E. S. Fedorov Promoting the Russian-German Scientific Interrelationship

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 181 ◽  
Author(s):  
Peter Paufler ◽  
Stanislav K. Filatov
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Analysis ◽  
Crystalline State ◽  
Crystal Structure Analysis ◽  
Present Knowledge ◽  
Personal Contact ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Impact

At the dawn of crystal structure analysis, the close personal contact between researchers in Russia and Germany, well documented in the “Zeitschrift für Krystallographie und Mineralogie”, contributed significantly to the evolution of our present knowledge of the crystalline state. The impact of the Russian crystallographer E. S. Fedorov upon German scientists such as A. Schoenflies and P. Groth and the effect of these contacts for Fedorov are highlighted hundred years after the death of the latter. A creative exchange of ideas paved the way for the analysis of crystal structures with the aid of X-ray diffraction.

Molecular Motion and Conformational Interconversion of Azobenzenes in Crystals as Studied by X-ray Diffraction

1997 ◽  
Vol 53 (4) ◽  
pp. 662-672 ◽  
Author(s):  
J. Harada ◽  
K. Ogawa ◽  
S. Tomoda
Keyword(s):  
Temperature Dependence ◽  
Crystal Structures ◽  
Torsional Vibration ◽  
Molecular Motion ◽  
X Ray Diffraction ◽  
Dynamic Disorder ◽  
X Ray ◽  
Conformational Interconversion ◽  
Free Molecules

Crystal structures of (E)-azobenzene (1), (E)-2,2′- dimethylazobenzene (2), (E)-3,3′-dimethylazobenzene (3) and (E)-4,4′-dimethylazobenzene (4) were determined by X-ray diffraction at various temperatures. An apparent shrinkage of the N=N bond and its temperature dependence were observed and are interpreted in terms of an artifact caused by the torsional vibration of the N—Ph bonds in crystals. In the crystal structures of (1), (3) and (4) the dynamic disorder was observed. The disorder is accounted for by the torsional vibration whose amplitude is large enough to give rise to the conformational interconversion. No disorder was observed for a crystal of (2). This is ascribed to the large difference in energy of the two conformers as free molecules. The true length of the N=N bond in azobenzenes was estimated to be 1.26–1.27 Å.

Temperature dependence of the AV3O7 (A = Ca, Sr) structure

2007 ◽  
Vol 63 (6) ◽  
pp. 836-842 ◽  
Author(s):  
Sebastian Prinz ◽  
Karine M. Sparta ◽  
Georg Roth
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Crystal Structures ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
Temperature Ranges ◽  
First Time

The V4+ (spin ½) oxovanadates AV3O7 (A = Ca, Sr) were synthesized and studied by means of single-crystal X-ray diffraction. The room-temperature structures of both compounds are orthorhombic and their respective space groups are Pnma and Pmmn. The previously assumed structure of SrV3O7 has been revised and the temperature dependence of both crystal structures in the temperature ranges 297–100 K and 315–100 K, respectively, is discussed for the first time.

Crystallization and preliminary analysis of a DNA dodecamer of d(CGCGmo6AATCCGCG) containing 2′-deoxy-N 6-methoxyadenosine: change in crystal packing with different humidity

1999 ◽  
Vol 55 (4) ◽  
pp. 873-876 ◽  
Author(s):  
Toshiyuki Chatake ◽  
Tomoko Sunami ◽  
Akira Ono ◽  
Yoshihito Ueno ◽  
Akira Matsuda ◽  
...  
Keyword(s):  
Phase Transition ◽  
Contact Angle ◽  
Data Collection ◽  
Crystal Structures ◽  
Preliminary Analysis ◽  
Crystal Packing ◽  
Base Pairing ◽  
X Ray ◽  
Dna Dodecamer

The DNA dodecamer of (CGCGmo6AATCCGCG) containing 2′-deoxy-N 6-methoxyadenosine has been crystallized for X-ray analysis in order to investigate the effects of the modified adenosine on base pairing. It has been found that the crystal changes from one form to another during data collection in a manner similar to a phase transition. The two crystal structures show that this phenomenon, ascribed to differences in humidity, is correlated with a change in the contact angle between the two duplexes.

Zur Reaktion von [MCl2(PR3)2] (M = Ni, Pd) mit E(SiMe3)2 (E = S, Se) Die Kristallstrukturen von [Ni3S2Cl2(PPh3)4], [Pd3S2Cl2(PPh3)4], INi3Se2(SeSiMe3)2(P(C2H4Ph)3)4] und [Pd3Se2(SeSiMe3)2(PPh3)4] / Reaction of [MCl2(PR3)2] (M = Ni, Pd) with E(SiMe3)2 (E = S, Se) The Crystal Structures of [Ni3S2Cl2(PPh3)4], [Pd3S2Cl2(PPh3)4], [Ni3Se2(SeSiMe3)2(P(C2H4Ph)3)4] and [Pd3Se2(SeSiMe3)2(PPh3)4]

1990 ◽  
Vol 45 (2) ◽  
pp. 127-133 ◽  
Author(s):  
Dieter Fenske ◽  
Holm Fleischer ◽  
Harald Krautscheid ◽  
Jörg Magull
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
X Ray ◽  
Triangular Clusters

[MC12(PR3)2] (M = Ni, Pd) reacts with E(SiMe3)2 (E = S, Se) to form triangular clusters, [Ni3S2Cl2(PPh3)4] (1), [Pd3S2Cl2(PPh3)4] (2), [Ni3Se2(SeSiMe3)2(P(C2H4Ph)3)4] (4) and [Pd3Se2(SeSiMe3)2(PPh3)4] (3). 1-4 have been characterized by X-ray crystal structure analysis. All these compounds contain a triangular M3-core, which is capped by two μ3-E-ligands (E = S in 1, Se in 3 and 4).

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