Vibrational spectra and proposed crystal structure of some tetraphenylarsonium compounds

1970 ◽  
Vol 48 (16) ◽  
pp. 2637-2639 ◽  
Author(s):  
L. K. Walford ◽  
Richard J. Blattner ◽  
Stephen Feldman ◽  
R. L. Bain
Keyword(s):  
Crystal Structure ◽  
Crystal Field ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Vibrational Spectra ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Unit Cells ◽  
Infrared Absorption Spectra

The crystal structures of (C6H5)4AsBF4, (C6H5)4AsPF6, (C6H5)4AsAsF6, and (C6H5)4AsSbF6 have been studied by X-ray diffraction. The unit cells are all tetragonal. The fluoroborate compound is probably isostructural with (C6H5)4AsFeCl4. The other three compounds are almost isostructural with (C6H5)4AsFeCl4, the only change being the accommodation of the dipyramidal PF6− ion in the space group [Formula: see text] (No. 82). Infrared absorption spectra are in general agreement with previous work on tetraphenylarsonium halides and compounds with hexafluoro Group VA ions. It is concluded that crystal field effects for this series of salts do not markedly affect the vibrational spectra.

Conversion of Monetite, CaHPO4, To Apatites: Effect of Carbonate on the Crystallinity and the Morphology of the Apatite Crystallites

1970 ◽  
Vol 14 ◽  
pp. 57-66 ◽  
Author(s):  
Racquel Z. LeGeros ◽  
John P. LeGeros ◽  
Otto R. Trautz ◽  
W. Paul Shirra
Keyword(s):  
Crystallite Size ◽  
Diffraction Pattern ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Carbonate Content ◽  
Structural Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbonate Solutions ◽  
Infrared Absorption Spectra

AbstractThe incorporation of carbonate in the apatite causes a decrease in crystallite size as demonstrated in precipitated apatites prepared at 37°C. Carbonate disturbs the crystallization of the growing apatite crystallites to such an extent that materials with more than 15 wt% CO3 gives an ‘amorphous’ x-ray diffraction pattern. The incorporation of carbonate in precipitates prepared at 100°C. causes a shortening of the a-axis and a lengthening of the c-axis which is proportional to the carbonate content, supporting the concept that in these apatites, CO3 substitutes for PO4 (11). X-ray diffraction linebroadening studies of CO3-apatites precipitated at 100°C and electron micrographs show that the size and shape of the crystallites change from long needles to smaller rods to tiny spheroids, depending upon the amount of CO3. Carbonate causes the bonding in the apatite to become weaker and more isotropic, which results in the small spheroidal crystals.This paper reports the effect of carbonate on lattice parameters and morphology of carbonate-apatites which have been prepared by the conversion of rnonetite, CaHPO4 in hot carbonate solutions. The structural effects of CO3 on the apatite is further reflected by the modification of the vibrations of the PO4 groups in the infrared absorption spectra. The morphology of ‘amorphous’ CO3- containing apatitic precipitates and that of CO3∼apatite with high CO3 content (prepared at 100°C) is similar, i.e., spheroidal in shape, but greatly differing in crystallite size.

PHASE TRANSITION IN LAYERED PEROVSKITE LIKE MANGANATE Ca3Mn2O7 UNDER HIGH PRESSURE

2001 ◽  
Vol 15 (18) ◽  
pp. 2491-2497 ◽  
Author(s):  
J. L. ZHU ◽  
L. C. CHEN ◽  
R. C. YU ◽  
F. Y. LI ◽  
J. LIU ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
The Other ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Diamond Anvil

In situ high pressure energy dispersive X-ray diffraction measurements on layered perovskite-like manganate Ca 3 Mn 2 O 7 under pressures up to 35 GPa have been performed by using diamond anvil cell with synchrotron radiation. The results show that the structure of layered perovskite-like manganate Ca 3 Mn 2 O 7 is unstable under pressure due to the easy compression of NaCl-type blocks. The structure of Ca 3 Mn 2 O 7 underwent two phase transitions under pressures in the range of 0~35 GPa. One was at about 1.3 GPa with the crystal structure changing from tetragonal to orthorhombic. The other was at about 9.5 GPa with the crystal structure changing from orthorhombic back to another tetragonal.

Molecular tapes in the structure of isoguaninium chloride

2017 ◽  
Vol 74 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Urszula Anna Budniak ◽  
Paulina Maria Dominiak
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Charge Density ◽  
Interaction Energy ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Structure

Isoguanine, an analogue of guanine, is of intrinsic interest as a noncanonical nucleobase. The crystal structure of isoguaninium chloride (systematic name: 6-amino-2-oxo-1H,7H-purin-3-ium chloride), C5H6N5O+·Cl−, has been determined by single-crystal X-ray diffraction. Structure analysis was supported by electrostatic interaction energy (E es) calculations based on charge density reconstructed with the UBDB databank. In the structure, two kinds of molecular tapes are observed, one parallel to (010) and the other parallel to (50\overline{4}). The tapes are formed by dimers of isoguaninium cations interacting with chloride anions. E es analysis indicates that cations in one kind of tape are oriented so as to minimize repulsive electrostatic interactions.

Crystal Structure of Calcium Picrate Pentahydrate: A New Eight-Coordinate Stereochemistry for [M(bidentate)2(unidentate)4]

1979 ◽  
Vol 32 (2) ◽  
pp. 301 ◽  
Author(s):  
V Diakiw ◽  
TW Hambley ◽  
DL Kepert ◽  
CL Raston ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Single Crystal ◽  
Title Compound ◽  
Lattice Site ◽  
The Other ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Triangular Face ◽  
X Ray

The crystal structure of the title compound, Ca(C6H2N307)2,5H2O, has been determined by single-crystal X-ray diffraction at 295(1) K and refined by least squares to a residual of 0.049 for 1513 'observed' reflections. Crystals are orthorhombic, Pmab, a 24.169(6), b l0.292(7), c 8.554(2) �, Z 4. The stereochemistry about the calcium has not been observed previously for the system [M(bidentate)2- (unidentate)4]; in the present structure, the calcium is coordinated by a pair of bidentate picrate ligands and the four water molecules in an array in which three of the water molecules occupy a triangular face of a square antiprism, the overall array having m symmetry. The remaining water molecule occupies a lattice site with no close interaction with the other species.

Synthesis and Structure of and Cation Distribution in the Zirconium Cluster Rb[(Zr6C)Cl15]

2008 ◽  
Vol 63 (5) ◽  
pp. 507-512 ◽  
Author(s):  
Henning W. Rohm ◽  
Martin Köckerling
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Cation Distribution ◽  
Type Structure ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coulombic Interactions ◽  
Cluster Network ◽  
Zirconium Cluster

Rb[(Zr6C)Cl15] was prepared by heating ZrCl4, Zr powder, RbCl and Al4C3 at 850 °C for 21 days. The crystal structure was determined by single crystal X-ray diffraction (space group Pmma, a = 18.484(3), b = 18.962(2), c = 9.708(1) Å, V = 2505.4(6) Å3, and Z = 4). Rb[(Zr6C)Cl15] crystallises in the Cs[Nb6Cl15]-type structure. It is built up from two interconnected types of cluster chains, one with linear Zr−Cla−a-Zr bridges, the other one with bent bridges. The rubidium cations are spread over three different sites within the cluster network which differs significantly from the cation distribution in the comparable potassium and caesium phases. The cation distribution can be rationalised considering the size of the cavities and the Coulombic interactions.

A New Bis-Tröger's Base: Synthesis, Spectroscopy, Crystal Structure and Isomerization

2006 ◽  
Vol 71 (9) ◽  
pp. 1278-1302 ◽  
Author(s):  
Martin Valík ◽  
Pavel Matějka ◽  
Eberhardt Herdtweck ◽  
Vladimír Král ◽  
Bohumil Dolensky
Keyword(s):  
Crystal Structure ◽  
Spectroscopic Data ◽  
The Other ◽  
X Ray Diffraction ◽  
One Pot ◽  
Molecular Tweezers ◽  
X Ray ◽  
Troger's Base ◽  
Ir And Raman ◽  
C Nmr

A new bis-Tröger's base was prepared from a tetraamine precursor as a mixture of two diastereoisomers. One of the isomers has a chair-like geometry, and the other possesses a boat-like geometry, embodying molecular tweezers. A one-pot preparation of bis-TB isomers and their interconversion under acid conditions was also studied. Structures of both isomers were confirmed by single-crystal X-ray diffraction. Extensive spectroscopic data, including 1H and 13C NMR, IR and Raman spectra of the isomers, are given.

A refinement of the dickite structure and some remarks on polymorphism in kaolin minerals

1961 ◽  
Vol 32 (252) ◽  
pp. 683-704 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Crystal Structure ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Structural Features ◽  
Mirror Image ◽  
Hydrogen Atoms ◽  
Octahedral Layer ◽  
Layer Structures ◽  
Infrared Absorption Spectra ◽  
Interlayer Bonding

SummaryThe crystal structure of the clay mineral dickite (Al2Si2H4O9) has been refined to a greater accuracy than that reported in an earlier analysis. Improved lattiçe parameters are: a 5·15±0·001, b 8·940±0·001, c 14·424 ± 0·002Å., β 96° 44′± 1′. The dickite structure shows several significant distortions from the geometry of the idealized kaolin layer, including deformation and rotation of the silica tetra-hedra. The most striking features of the octahedral layer are the extremely short shared edges of 2·37 Å. Although the analysis was not sufficiently accurate to position the hydrogen atoms with certainty, a model consistent with the infrared absorption spectra is proposed. The stacking sequences of kaolin-layer minerals have been considered with reference to the structural features observed in dickite. There are thirty-six ways of superposing two kaolin layers commensurate with the OH-O bonds found in kaolinite, dickite, and nacrite. The twelve sequences showing the least amount of cation-cation superposition between consecutive kaolin layers can be used to construct two one-layer cells, kaolinite and its mirror image, and twelve two-layer cells, including dickite and nacrite. The distortions of the kaolin layer introduce secondary variations in the interlayer bonding that suggest that dickite and nacrite are the most stable of the kaolin layer structures, since they possess the shortest oxygen-hydroxyl contacts.

ISOLATION AND IDENTIFICATION OF TWO PHENAZINES FROM A STRAIN OF PSEUDOMONAS AUREOFACIENS

1965 ◽  
Vol 43 (9) ◽  
pp. 1055-1062 ◽  
Author(s):  
J. I. Toohey ◽  
C. D. Nelson ◽  
G. Krotkov
Keyword(s):  
Carboxylic Acid ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Chemical Properties ◽  
The Other ◽  
Isolation And Identification ◽  
Pseudomonas Aureofaciens ◽  
Infrared Absorption Spectra

A method is described for the purification of two phenazine compounds from cultures of a strain of Pseudomonas aureofaciens. The chemical properties of the compounds are described and the ultraviolet, visible, and infrared absorption spectra are shown. One compound is identified as phenazine-1-carboxylic acid and the other is probably 2-hydroxyphenazine-1-carboxylic acid.

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