Synthesis, reactivity, and the electronic structures of fluoro- and hydridophosphazene anions: x-ray crystal structure of [Li(THF)3][N3P3F2H(BEt3)(.eta.-C5H4)2Fe]

1991 ◽  
Vol 10 (9) ◽  
pp. 3090-3098 ◽  
Author(s):  
Harry R. Allcock ◽  
William D. Coggio ◽  
Ian. Manners ◽  
Masood. Parvez
Keyword(s):  
Crystal Structure ◽  
Electronic Structures ◽  
X Ray

An experimental and theoretical approach to the study of the properties of parabanic acid and related compounds: synthesis and crystal structure of diethylimidazolidine-2-selone-4,5-dione

2000 ◽  
Vol 78 (9) ◽  
pp. 1147-1157
Author(s):  
Massimiliano Arca ◽  
Francesco Demartin ◽  
Francesco A Devillanova ◽  
Francesco Isaia ◽  
Francesco Lelj ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Dft Calculations ◽  
Electronic Structures ◽  
Frontier Orbitals ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Related Compounds ◽  
Donor Character ◽  
Ft Raman

The syntheses of the first examples of selenoparabanic acid derivatives (dialkylimidazolidine-2-selone-4,5-dione, 3eR R = Me, Et, Bu) are presented along with the X-ray crystal structure determination of 3eEt. To gain an insight in the properties of parabanic acid derivatives on the basis of their electronic structures, we report the results of comparative hybrid-DFT calculations performed on parabanic, thioparabanic, and selenoparabanic acids (3aH, 3bH, and 3eH) and on their N,N' -dimethyl derivatives (3aMe, 3bMe, and 3eMe). Calculations show that the different nature of the frontier orbitals of 3aR compared to those of 3bR and 3eR, might account for the different reactivities of these compounds. Moreover, the weak donor character of 3bR and 3eR towards molecular di-iodine, estimated by FT-Raman measurements is in agreement with the calculated NBO-charge distribution.Key words: selenation, selenoparabanic derivatives, crystal structure, DFT calculations.

Article

1998 ◽  
Vol 76 (3) ◽  
pp. 307-312
Author(s):  
A Wallace Cordes ◽  
Robert C Haddon ◽  
Robin G Hicks ◽  
Richard T Oakley ◽  
Kristen E Vajda
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Magnetic Susceptibility ◽  
Electronic Structure ◽  
Charge Transfer ◽  
Electronic Structures ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Diamagnetic State

Electroreduction of the 2,5-thiophene-bridged bis(1,2,3,5-diselenadiazolylium) salt [T-2,5-Se][SbF6]2 in acetonitrile, at a Pt wire and in the presence of iodine, affords a highly conductive ( sigma = 102 S cm-1 at 293 K) 1:1 charge-transfer (CT) salt [T-2,5-Se][I], the crystal structure of which has been determined by single-crystal X-ray diffraction. The crystals belong to the orthorhombic space group Fm2m, a = 3.544(2), b = 10.9808(16), c = 31.464(5) Å , V = 1224.5(7) Å 3. The structure consists of perfectly superimposed pi -stacks of molecular units bridged by columns of disordered iodines. This packing motif is similar to that of the related 1,3-benzene-bridged derivative [1,3-Se][I], but the lateral intermolecular Se···Se interactions linking adjacent pi -stacks are considerably shorter, indicative of a more isotropic electronic structure for [T-2,5-Se][I]. Magnetic susceptibility measurements on [T-2,5-Se][I] nonetheless indicate a phase transition to a diamagnetic state near 200 K, behaviour similar to that observed for [1,3-Se][I]. The electronic structures and transport properties of the two compounds are discussed in the light of extended Hückel band-structure calculations.Key words: diselenadiazolyl, diradical, charge-transfer salt, magnetic susceptibility, crystal structure.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

X-ray Crystal Structure of ?9-THC-tosylate

Planta Medica ◽  
2008 ◽  
Vol 74 (03) ◽  
Author(s):  
W Gul ◽  
P Carvalho ◽  
D Slade ◽  
M Avery ◽  
JR Duchek ◽  
...  
Keyword(s):  
Crystal Structure ◽  
X Ray

Crystal structure of an inclusion complex between chiral monoaza-15-crown-5 and S(–)-1-phenyl-ethyl ammonium percholorate

2003 ◽  
Vol 218 (5) ◽  
Author(s):  
Süheyla Özbey ◽  
F. B. Kaynak ◽  
M. Toğrul ◽  
N. Demirel ◽  
H. Hoşgören
Keyword(s):  
Crystal Structure ◽  
Inclusion Complex ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
New Type

AbstractA new type of inclusion complex, S(–)-1 phenyl ethyl ammonium percholorate complex of R-(–)-2-ethyl - N - benzyl - 4, 7, 10, 13 - tetraoxa -1- azacyclopentadecane, has been prepared and studied by NMR, IR and single crystal X-ray diffraction techniques. The compound crystallizes in space group

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

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