Etude structurale par diffraction des RX et spectroscopie IR des hydrates 10 et 8.4 Å de kaolinite

1999 ◽  
Vol 32 (5) ◽  
pp. 968-976 ◽  
Author(s):  
S. Jemai ◽  
A. Ben Haj Amara ◽  
J. Ben Brahim ◽  
A. Plançon
Keyword(s):  
Water Molecule ◽  
Octahedral Site ◽  
Ammonium Fluoride ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Tetrahedral Sheet ◽  
X Ray ◽  
Octahedral Sites ◽  
Sheet Structure

Two hydrated kaolinites, characterized by 10 and 8.4 Å basal distances, were synthesized by treating the kaolinite KGa-1 with dimethyl sulfoxide (DMSO) and ammonium fluoride (NH4F). The X-ray diffraction study was based on a comparison between the experimental and calculated profiles. This study was conducted in two steps: firstly, the study of the 00lreflections enabled the determination of the stacking mode alongc*, the number of water molecules and their positions along the normal to the plane of the sheet structure; secondly, the study of thehkbands, withhand/ork≠ 0, enabled the determination of the stacking mode and the positions of the water molecules in the (a,b) plane. The 10 Å hydrated kaolinite is characterized by two water molecules per Al2Si2O5(OH)4unit, situated at 3 and 3.4 Å from the hydroxyl surface, over the octahedral sites. Two adjacent layers are translated with respect to each other, withT11= −0.38a− 0.37b+ 10n. The 8.4 Å hydrated kaolinite is characterized by one water molecule per Al2Si2O5(OH)4unit, situated at 2.4 Å from the hydroxyl surface and inserted between the vacant octahedral site and the ditrigonal cavity of the tetrahedral sheet. The corresponding interlayer shift isT11= −0.355a+ 0.35b+ 8.4n.

Étude par Diffraction X des Modes d'Empilement de la Nacrite Hydratée et Deshydratée

1998 ◽  
Vol 31 (5) ◽  
pp. 654-662 ◽  
Author(s):  
A. Ben Haj Amara ◽  
J. Ben Brahim ◽  
A. Plançon ◽  
H. Ben Rhaiem
Keyword(s):  
Water Molecule ◽  
Octahedral Site ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
Natural Mineral ◽  
Tetrahedral Sheet ◽  
X Ray ◽  
Basal Distance ◽  
Interlamellar Space

X-ray diffraction based on the comparison of experimental and calculated powder profiles enabled the determination of the structural characteristics of hydrated and dehydrated Tunisian nacrite. Using the concept describing the structure of natural nacrite, the stacking mode of the layers in the hydrated and dehydrated nacrite has been determined. The hydrate is characterized by an 8.42 Å basal distance; one water molecule per Si2Al2O5(OH)4is intercalated in the interlamellar space, located above the vacant octahedral site of the layer atz= 6.5 Å and inserted inside the ditrigonal cavity of the tetrahedral sheet of the upper layer. The dehydrated nacrite obtained by heating of the hydrate at 423 K has the same interlayer shiftt= −0.35aas the natural nacrite. Coherence domain sizes alongc^{\ast} and in theabplane are the same as those in the hydrate but different from those of the natural mineral. After dehydration, 5% of the layers had an interlayer shift similar to that obtained from the hydrate.

Etude structurale d'un hydrate 10 Å instable de kaolinite

2000 ◽  
Vol 33 (4) ◽  
pp. 1075-1081 ◽  
Author(s):  
S. Jemai ◽  
A. Ben Haj Amara ◽  
J. Ben Brahim ◽  
A. Plançon
Keyword(s):  
Dimethyl Sulfoxide ◽  
Structural Characteristics ◽  
Ammonium Fluoride ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Basal Distance

The treatment of KGa-1 kaolinite with dimethyl sulfoxide and ammonium fluoride heated at 383 K provides an unstable hydrated phase characterized by a 10 Å basal distance. When air-dried, this hydrate gives a dehydrated phase at 7.15 Å. The aim of this work is to determine the structural characteristics of this hydrate. The method used to characterize this hydrate is based on the comparison between experimental and calculated X-ray diffraction profiles. This study is achieved in two steps: the study of 00lreflections enabled the determination of the number of intercalated water molecules, their positions and the stacking mode along the normal to the (a,b) plane; and the study of thehklreflections withhand/ork≠ 0 enabled the determination of the stacking mode and the positions of water molecules in the (a,b) plane. The unstable hydrate is characterized by two water molecules per Al2Si2O5(OH)4unit situated atz1=z2= 7.57 Å. Two adjacent layers are translated with respect to each other withTI= −0.155a+ 0.13b+ 10n.

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, crystal structure, and vibrational spectra of the complex maleic acid•2H2O•18-crown-6

1990 ◽  
Vol 68 (12) ◽  
pp. 2183-2189 ◽  
Author(s):  
Pierre Audet ◽  
Rodrigue Savoie ◽  
Michel Simard
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Maleic Acid ◽  
Water Molecules ◽  
Infrared And Raman Spectra ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
O 18 ◽  
Stoichiometric Complex

A stoichiometric complex of formula maleic acid•2H2O•18-crown-6 has been obtained from maleic acid and the macrocyclic polyether 18-crown-6. Crystals of this complex have been shown by X-ray diffraction crystallography to belong to the Cc space group of the monoclinic system. The acid molecules in the adduct are linked to each other through a water molecule, giving infinite [-acid-H2O-]n chains. They are also linked to the crown ether via water molecules. The infrared and Raman spectra of the complex are presented and compared to those of crystalline maleic acid. Keywords: maleic acid/18-crown-6, structure, X-ray, spectra.

scholarly journals Calcioferrite with composition (Ca3.94Sr0.06)Mg1.01(Fe2.93Al1.07)(PO4)6(OH)4·12H2O

2014 ◽  
Vol 70 (3) ◽  
pp. i16-i17
Author(s):  
Barbara Lafuente ◽  
Robert T. Downs ◽  
Hexiong Yang ◽  
Robert A. Jenkins
Keyword(s):  
Single Crystal ◽  
Water Molecules ◽  
Site Symmetry ◽  
Natural Sample ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Bonding Interactions ◽  
Small Crystals ◽  
Hydrated Calcium

Calcioferrite, ideally Ca4MgFe3+4(PO4)6(OH)4·12H2O (tetracalcium magnesium tetrairon(III) hexakis-phosphate tetrahydroxide dodecahydrate), is a member of the calcioferrite group of hydrated calcium phosphate minerals with the general formula Ca4AB4(PO4)6(OH)4·12H2O, whereA= Mg, Fe2+, Mn2+andB= Al, Fe3+. Calcioferrite and the other three known members of the group, montgomeryite (A= Mg,B= Al), kingsmountite (A= Fe2+,B= Al), and zodacite (A= Mn2+,B= Fe3+), usually occur as very small crystals, making their structure refinements by conventional single-crystal X-ray diffraction challenging. This study presents the first structure determination of calcioferrite with composition (Ca3.94Sr0.06)Mg1.01(Fe2.93Al1.07)(PO4)6(OH)4·12H2O based on single-crystal X-ray diffraction data collected from a natural sample from the Moculta quarry in Angaston, Australia. Calcioferrite is isostructural with montgomeryite, the only member of the group with a reported structure. The calcioferrite structure is characterized by (Fe/Al)O6octahedra (site symmetries 2 and -1) sharing corners (OH) to form chains running parallel to [101]. These chains are linked together by PO4tetrahedra (site symmetries 2 and 1), forming [(Fe/Al)3(PO4)3(OH)2] layers stacking along [010], which are connected by (Ca/Sr)2+cations (site symmetry 2) and Mg2+cations (site symmetry 2; half-occupation). Hydrogen-bonding interactions involving the water molecules (one of which is equally disordered over two positions) and OH function are also present between these layers. The relatively weaker bonds between the layers account for the cleavage of the mineral parallel to (010).

Experimental determination of electrostatic properties of Na–X zeolite from high resolution X-ray diffraction

2014 ◽  
Vol 16 (24) ◽  
pp. 12228-12236 ◽  
Author(s):  
F. F. Porcher ◽  
M. Souhassou ◽  
C. E. P. Lecomte
Keyword(s):  
High Resolution ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Cation Site ◽  
X Ray ◽  
X Zeolite ◽  
Adsorption Of Water ◽  
Zeolite P ◽  
Resolution Single

High resolution single crystal X-ray diffraction is used to obtain the electron density and atomic charges in Na–X zeolite. The Coulomb potential and interaction energies are calculated for a given Na+ distribution and are discussed in connection with cation site affinities and adsorption of water molecules in the zeolite.

The structure determination of a binuclear copper(II) complex of aTetra-Schiff base macrocycle

1976 ◽  
Vol 29 (3) ◽  
pp. 515 ◽  
Author(s):  
BF Hoskins ◽  
NJ McLeod ◽  
HA Schaap
Keyword(s):  
Schiff Base ◽  
Least Squares Method ◽  
Condensation Product ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Binuclear Copper ◽  
Apical Position ◽  
X Ray ◽  
Space Groups

The structure of the complex Lcu2Cl2,6H2O (where LH2 is the tetra-Schiff base macrocycle formed as the condensation product of propane-1,3-diamine and 2-hydroxy-5-methylisophthal- aldehyde in the mole ratio 2: 2) was determined by single-crystal X-ray diffraction methods. The crystals are monoclinic, a 7.720(1), b 17.079(1), c 11.171(1) � and β 91.50(1)�, with two molecules per unit cell. It has proved difficult to resolve the ambiguity between the three possible space groups (C2, Cm, and C2/m) and the initial model has been refined in each using a full-matrix least-squares method. The space group C2/m seems the most likely and the structure is described in it; R 0.049 for the 1369 independent reflections measured using counter methods. The structure analysis has confirmed the anticipated cyclic structure of the ligand with the two copper atoms held together in a binuclear arrangement by the planar N4O2 donor set; the Cu.. .Cu distance is 3.133(1)�. Each copper atom has a distorted square-pyramidal environment with the apical position of each being occupied by a chlorine atom; the two chlorine atoms are on the opposite sides of the macrocycle. The water molecules are not coordinated, but form an extensive system of hydrogen bonding throughout the crystal with discrete binuclear molecules of the LCu2Cl2 complex.

NEUTRON DIFFRACTION DETERMINATION OF THE HYDROGEN POSITIONS IN NATROLITE

1964 ◽  
Vol 42 (2) ◽  
pp. 229-240 ◽  
Author(s):  
B. H. Torrie ◽  
I. D. Brown ◽  
H. E. Petch
Keyword(s):  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Oxygen Atom ◽  
Water Molecule ◽  
Neutron Diffraction Data ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Diffraction Determination

Neutron diffraction data obtained with single crystals of natrolite, Na2Al2Si3O10.2H20, have been analyzed using Fourier difference synthesis arid least squares methods. The details of the aluminosilicate framework were found to be in agreement with the results of earlier X-ray diffraction studies. The oxygen atom of the water molecule is linked by bent hydrogen bonds to two oxygen atoms in the framework, making an O—O—O angle of 134°. Lying almost in the O—O—O plane, the hydrogen atoms are located at distances of 0.94 ± 0.03 and 0.98 ± 0.02 Å from the oxygen of the water molecule and make with it an H—O—H angle of 108°. Natrolite thus provides an excellent example of the ability of the water molecule to resist the influence of the environment in opening the H—O—H angle.

scholarly journals SYNTHESIS AND STRUCTURE OF 4-(9-HYDROXY-1,4,7-TRIOXYNONYL)PHTHALONITRILE

2017 ◽  
Vol 60 (3) ◽  
pp. 15
Author(s):  
Alexandra S. Kuznetsova ◽  
Maksim V. Dmitriev ◽  
Alexander V. Zav’yalov ◽  
Oscar I. Koifman ◽  
Mikhail K. Islyaikin
Keyword(s):  
Water Molecule ◽  
Ethyl Acetate ◽  
Theoretical Calculations ◽  
Triethylene Glycol ◽  
Solvent Evaporation ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Intermolecular Hydrogen Bonds ◽  
Reduced Pressure ◽  
X Ray

4-(9-Hydroxy-1,4,7-trioxynonyl)phthalonitrile was prepared by reaction of 4-nitrophthalonitrile with triethylene glycol in dry DMSO in the presence of fresh-calcined fine milled K2CO3 at 60 °C for 12 hours. The reaction mixture was poured into cold distilled water and extracted by CH2Cl2. Then the crude product obtained after solvent evaporation was purified by column chromatography on silica gel using elution mixture of ethyl acetate : hexane (1:3) and after that end product was dried at reduced pressure at 80 oC for 4 h. The product was characterized by IR and 1Н NMR spectroscopies, mass-spectrometry, elemental analysis and X-ray diffraction data. In MALDI-TOF spectrum, two signals located at 299 [M+Na]+  and 315 [M+К]+ Da were detected. Conformity between the calculated isotopic distributions and those derived from experimental data proves these assignments. A colorless monocrystal suitable for X-Ray measurements was grown up by low temperature solvent evaporation from a solution of 4-(9-hydroxy-1,4,7-trioxynonyl)phthalonitrile in ethyl acetate. X-ray studying showed that this compound is a monohydrate of 4-(9-hydroxy-1,4,7-trioxynonil)phthalonitrile with a water molecule located in lateral chain. Four molecules of 4-(9-hydroxy-1,4,7-trioxynonil)phthalonitrile and four water molecules were founded to be located in one unit cell with formatting eight intermolecular hydrogen bonds. Hence triethylene glycol fragment forms a chelate-like cavity which is able to hold a water molecule or a cation of alkali metal. It was found that its structure is very similar to that optimized at DFT/B3LYP/6-31G(d,p) level. The some bond lengths of theoretical calculations are found to be greater than experiment data because of close intermolecular interactions in solid state.Forcitation:Kuznetsova A.S., Dmitriev M.V., Zav’yalov A.V., Koifman O.I., Islyaikin M.K. Synthesis and structure of 4-(9-hydroxy-1,4,7-trioxynonyl)phthalonitrile. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 3. P. 15-21.

scholarly journals Pristine and hydrated fluoroapatite (0001)

2019 ◽  
Vol 75 (5) ◽  
pp. 830-838
Author(s):  
Xavier Torrelles ◽  
Immad M. Nadeem ◽  
Anna Kupka ◽  
Adrián Crespo-Villanueva ◽  
Sandrina Meis ◽  
...  
Keyword(s):  
Water Molecule ◽  
Experimental Analysis ◽  
Surface Coverage ◽  
Adsorbed Water ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Truncation Rod ◽  
Before And After ◽  
Dry Conditions

The surface structure of fluoroapatite (0001) (FAp0001) under quasi-dry and humid conditions has been probed with surface X-ray diffraction (SXRD). Lateral and perpendicular atomic relaxations corresponding to the FAp0001 termination before and after H2O exposure and the location of the adsorbed water molecules have been determined from experimental analysis of the crystal truncation rod (CTR) intensities. The surface under dry conditions exhibits a bulk termination with relaxations in the outermost atomic layers. The hydrated surface is formed by a disordered partially occupied H2O layer containing one water molecule (33% surface coverage) adsorbed at each of the three surface Ca atoms, and is coupled with one OH group randomly bonded to each of the three topmost P atoms with a 33% surface coverage.

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