Bernard W . Liebich - Academia.edu (original) (raw)
Papers by Bernard W . Liebich
Thèse de Doctorat à l'Université de Genève, 1971
Le système luminescent H3BO3 / 2 - hydroxy - 4 - methoxy - 4’chloro - benzophenone (HMCB) / H2SO4... more Le système luminescent H3BO3 / 2 - hydroxy - 4 - methoxy - 4’chloro - benzophenone (HMCB) / H2SO4 conc. a d’abord été étudié par la méthode des variations continues mettant en évidence les complexes A1R2 et A2R2 . L’application d’autres méthodes faisant varier alternativement le ligand et l’atome central ont ensuite mis en évidence les complexes A1R1, A1R2 et A2R2 et leurs constantes globales apparentes ( β(ij) ) et coefficients d’efficacité apparents (ϕ(ij)). Un complexe solide de type A2R2 a aussi pu être isolé et analysé, présentant un noyau central à six atomes de B (2x), de S (1x) et d’O (3x), lié à deux réactifs (HMCB). Un schéma de réactions a ainsi pu être établi confirmant l’hypothèse de Langmyhr et Arnesen(32) selon laquelle H3BO3 peut former dans H2SO4 conc. avec certains réactifs des complexes de type A2R2 similaire à celui identifié ici. Pour pouvoir appliquer la méthode fluorimétrique à l’HMCB au dosage de traces de B en milieu H2SO4 conc. aux eaux, sols et plantes il a d’abord fallu éliminer les matières organiques et les traces de fluorescences résiduelles gênantes. Pour cela une minéralisation par voie humide par adjonction lors du chauffage, de gouttes de H2O2 (30%) à 3 ml de H2SO4 conc. a été développée. L’interférence d’ions métalliques est négligeable, celle de F- est faible et celle de NO3- et H2O2 peut être éliminée. Avec l’HMCB des nanogrammes de bore ont ainsi pu être dosés dans de nombreux très petits échantillons d’eaux, d’extraits de sols, d’humus et de plantes, avec des erreurs relatives (E%) ≤ à 10%. Il est d’un intérêt très spécial que avec l’application de la méthode à l’HMCB à des extraits d’humus solides et légers de différents sols Français, obtenus selon la méthode de Hardisson et al., des quantités de B de l’ordre de 10 ppm ont été trouvées. Ces fractions de l’humus fortement liées au bore pourraient même être une caractéristique essentielle des sols.
The luminescent system H3BO3 / 2 - hydroxyl - 4 - methoxy - 4’chloro - benzophenone (HMCB) / H2SO4 conc. was first studied by the method of the continuous variations to identify the complexes A1R2 and A2R2. Then further methods, based on the alternative variations of the ligand and the central atom, gave a more detailed view of the system and identified the complexes A1R1, A1R2 et A2R2 and their apparent global constants (β(ij) ) and apparent efficiency coefficients (ϕ(ij)). Also, a solid complex of the type A2R2 was isolated and analyzed, presenting a central hexagonal ring with the atoms: B (2x), S (1x) and O (3x), bound to two reagents (HMCB). A scheme of reactions could be established and the hypothesis of Langmyhr et Arnesen(32) confirmed, that H3BO3 can form in H2SO4 conc. with certain reagents, complexes of a A2R2 type similar to the one identified here. To be able to apply the fluorimetric HMCB method to determine traces of B in H2SO4 conc. in water, soils and plants it was necessary to eliminate the organic matter and traces of the residual fluorescence. A mineralization with addition of drops of H2O2 (30%), during the heating, to 3 ml of H2SO4 conc. was so developed. The interferences with metallic ions is negligible, the one of F- is low and that of NO3- and H2O2 can be canceled. So with this method it was possible to determine nanograms of boron in numerous very small samples of water, soil extracts, humus and plants with an relative errors (E%) ≤ to 10%. It is of outstanding interest that with the application of this method to the solid and light humus extracts of different French soils, obtained by extractions and concentrations according to Hardisson et al., quantities of B of the order of 10 ppm were found. These humus fractions strongly bound to boron, may well be an essential characteristic of soils
The crystal structure, including H positions, of the monoclinic zeolite mineral parthéite (space ... more The crystal structure, including H positions, of the monoclinic zeolite mineral parthéite (space group C2/c) of framework type-PAR from Denezhkin Kamen (Urals, Russia) was refined, from single-crystal X-ray data to R 1 = 3.46%. In addition, in situ single-crystal X-ray data have been measured in steps of 25 °C up to 375 °C to analyze dehydration behavior. In situ Raman spectra of the natural (room temperature) and partly dehydrated varieties of parthéite have been recorded at 100, 150, and 275 °C. The structure of parthéite, Ca 2 Al 4 Si 4 O 15 (OH) 2 ⋅4H 2 O, is characterized by a tetrahedral framework interrupted by an OH-group forming the apex of one AlO 4 tetrahedron. In addition, this OH-group coordinates extraframework Ca together with two H 2 O molecules and four framework oxygen sites. The structure has four strong hydrogen bonds with H•••O interactions below 2 Å. The fifth hydrogen associated with a H 2 O molecule, exhibits two potential acceptors of weak hydrogen bonds with H•••O distances of ca. 2.5 Å. This softly bound H 2 O molecule is released at 150 °C without severe impact on framework distortions but with decrease of Ca coordination from seven to six. Concurrently with loss of the second H 2 O molecule at 250 °C, the structure further compacts and becomes severely distorted. The space group C2/c and the tetrahedral connectivity are preserved but β changes from 91 to 79° and the volume drops from 1730 to 1600 Å 3. Ca is still six-coordinated by five framework O atoms and OH.
Compte rendu des séances de la Société de physique et d'histoire naturelle de Genève, 1980
Séance du 8 mai 1980 Une nouvelle variété de péridot de la série forstérite-téphroïte, de composi... more Séance du 8 mai 1980 Une nouvelle variété de péridot de la série forstérite-téphroïte, de composition Fo 60-Tp 40 •
Compte rendu des séances de la Société de physique et d'histoire naturelle de Genève, 1980
Bulltin suisse Minéral. Pétrogr., 1977
Chantalite, CaA]2Si04(OH)4, occurs with vuagnatite, prehnite, hydrogrossular, chlorite and calci... more Chantalite, CaA]2Si04(OH)4, occurs with vuagnatite, prehnite, hydrogrossular, chlorite
and calcite in rodingitic dykes from an ophiolitic zone in the Taurus Mountains,
southwest Turkey. The name is for Mrs. Chantal Sarp. Both name and mineral have been approved by the Commission on new Minerals and Mineral Names of the
International Mineralogical Association.
Electron microprobe analysis has shown the uniform distribution of the major
elements and the absence of other components. X-ray powder diffraction data are from a Gandolfi camera. The crystal system is tetragonal, and the cell parameters are: a 4.945 (3), c 23.27 (2) A. The probable space group is I4i/a. The major X-ray diffraction lines occur at 5.810, 4.828, 4.171, 3.349, 2.598, 2.235, 2.202, 1.749, 1.529, 1.453 and 1.301 A. Crystals are always anhedral, varying in size between 0.1 and 0.3 mm. The measured density is 2.8-2.9 g/cm3, the calculated densitiy being 2.97 g/cm3. The difference is due to difficulties in getting material free of inclusions. The refractive
indices are: o> 1.653, e= 1.642, optically negative. The crystallization of chantalite is
related to metasomatic processes of rodingitization.
Schweiz, mineralogische petrographische Mitteilungen, 1985
Defernite, a new mineral with an unusual structure is orthorhombic: Pnam, a= 17.860 (5), b 22.7... more Defernite, a new mineral with an unusual structure is orthorhombic: Pnam,
a= 17.860 (5), b 22.775 (6) and c 3.658 (1) Â. V 1487.9 Â2, Z 4, Dx 2.42, Dm 2.5 g/cm3. The structure was solved by direct methods and the use of the Fourier difference map. From the counter diffractometer data, the structure was refined isotropically to a final
Rw of 0.082, whereas the final R( was 0.142. Probably the refinement could not be persued further due to the quality of the crystal and because the structure of the mineral contains weakly bound water molecules difficult to locate and shows occasional replacement of (C03)2 or (OH)"1. In relation to the structure the difficulty of the analysis of a carbonate mineral by microprobe is discussed. The structure is formed along axis a, of ribbons, composed of CaOy (OH)x polyhedra surrounding the (C03)"2 groups and along axis c, of and along axis c, of infinite channels in which water molecules could be located.
Keywords .-Defernite, structure.
Mitteilungen aus Lebensmitteluntersuchung und Hygiene, 2003
Les contractions de volume des melanges des alcools monohydroxyles, methanol, 1- et 2-propanol et... more Les contractions de volume des melanges des alcools monohydroxyles, methanol, 1- et 2-propanol et tert-butanol, avec l'eau sont determinees ici en utilisant des methodes semblables a celles developpees dans nos etudes precedentes pour les melanges ethanol-eau. On obtient pour chacun des melanges alcool-eau des courbes de contractions, representees en fonction des %mas, %vol et %mol, caracteristiques en ce qui concerne leurs intensites et formes. En passant du methanol, 1- et 2-propanol au tert-butanol, on observe des courbes dont les maxima vont de 12 a 40 %mol, de 34 a 55 %mas et de 42 a 62 %vol. L'intensite des maxima des contractions variera aussi de maniere differente selon le genre d'alcool et la temperature. Ainsi, si pour le melange methanol-eau les variations des contractions en fonction de la temperature sont a peine perceptibles, pour les melanges des autres alcools elles sont tres nettement marquees. Les maxima des contractions donnees en fonction des %mol données en fonction des % donnent de précieuses indications sur la nature des associations entre les molécules d'alcoolet d'eau Avec l'aide de la méthode de Jobles rapports moléculaires i/j les plus probables dans les mélanges alcool / eau ont ainsi été déterminésA2W3 pour le méthanol, A1W5 pour le 2-propanol, A1W6 pour le 1-propanol et A1W7 pour le ter-butanol. Comme visiblement on trouve dans ces mélanges des association de type "cluster", la formation d'agrégats encore plus complexes de type ( AiWj) est aussi possible..
The wallpaper-type crystal structure of wightmanite, Mg5(BO3)O(OH)5·1–2H2O, has been reanalyzed i... more The wallpaper-type crystal structure of wightmanite, Mg5(BO3)O(OH)5·1–2H2O, has been reanalyzed in order to better understand the position and bonding of hydrogen atoms. Single-crystal structure refinement yielded the monoclinic I2/m unit cell a = 13.5165(18), b = 3.0981(3), c = 18.170(3)Å, ß = 91.441(6)°, and V = 760.65(17)Å3, Z = 4. Hydrogen atoms of OH groups pointing to the inside of the elliptical channels oriented parallel to [010] are arranged in the form of two overlying, a–c parallel planar pentagons. The two pentagons point in opposite directions. Hydrogen-bond analysis shows that the hydroxyl groups are linked by complex polyfurcated, intra-molecular hydrogen bonds forming a web-like network coating the walls of the channels. The longest distance between hydrogens (7.226 Å) is observed in the pentagonal planes of the channel. The anisotropically refined oxygen atoms of the zeolitic water show their strongest vibration parallel to the b axis and in the direction of the lar...
American Mineralogist, 2012
ABSTRACT The crystal structure, including H positions, of the monoclinic zeolite mineral parthéit... more ABSTRACT The crystal structure, including H positions, of the monoclinic zeolite mineral parthéite (space group C2/c) of framework type -PAR from Denezhkin Kamen (Urals, Russia) was refined, from single-crystal X‑ray data to R1 = 3.46%. In addition, in situ single-crystal X‑ray data have been measured in steps of 25 °C up to 375 °C to analyze dehydration behavior. In situ Raman spectra of the natural (room temperature) and partly dehydrated varieties of parthéite have been recorded at 100, 150, and 275 °C. The structure of parthéite, Ca2Al4Si4O15(OH)2⋅4H2O, is characterized by a tetrahedral framework interrupted by an OH-group forming the apex of one AlO4 tetrahedron. In addition, this OH-group coordinates extraframework Ca together with two H2O molecules and four framework oxygen sites. The structure has four strong hydrogen bonds with H···O interactions below 2 Å. The fifth hydrogen associated with a H2O molecule, exhibits two potential acceptors of weak hydrogen bonds with H···O distances of ca. 2.5 Å. This softly bound H2O molecule is released at 150 °C without severe impact on framework distortions but with decrease of Ca coordination from seven to six. Concurrently with loss of the second H2O molecule at 250 °C, the structure further compacts and becomes severely distorted. The space group C2/c and the tetrahedral connectivity are preserved but β changes from 91 to 79° and the volume drops from 1730 to 1600 Å3. Ca is still six-coordinated by five framework O atoms and OH.
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry
R= 0.051 for 937 reflexions measured at room temperature (20°C). An intramolecular asymmetrical h... more R= 0.051 for 937 reflexions measured at room temperature (20°C). An intramolecular asymmetrical hydrogen bond with O(1)-O(2)=2.55 A, is present. in Table 1, were refined by full-matrix least-squares calculation, the function minimized being ~co(AF2o) where co= 1/a2(Fo) (ORXFLS3 programme by Busing et al., 1971b). A list of structure factors is available.* * This table has been deposited with the British Library Lending Division as Supplementary Publication No. SUP 30539 (26 pp., 1 microfiche). Copies may be obtained through The
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry
Counter technique, direct methods, least-squares refinement, R=5.0% for 1268 reflexions measured ... more Counter technique, direct methods, least-squares refinement, R=5.0% for 1268 reflexions measured at 20°C (R~=2.5 %). An asymmetrical hydrogen bond with O(1)...O(2) 2.540 A is present. Comparison with 2-hydroxy-4-methoxybenzophenone (HMB) is made and similarities and differences discussed. HMB and HMCB are non-planar and in both cases the crystal is composed of pairs of centrosymmetrically related molecules. The short intermolecular CI...C1 distances for HMCB and the presence of pairs of molecules for both compounds are important features. The present results may also add to the knowledge of the optical filter effect of this family of substances.
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry
Counter technique, direct methods, least-squares refinement, R=6.2% (Rw=2"2%) for 1258 reflexions... more Counter technique, direct methods, least-squares refinement, R=6.2% (Rw=2"2%) for 1258 reflexions measured at 20°C. The C-nucleoside CPOP is of interest as an analogue of pyrazomycin, an antitumour and antiviral antibiotic. In this fl-anomer, the erythrofuranosyl moiety is found in an unusual conformation with a torsion angle N(2)-C(1)-C(I')-O(I') [X] equal to 122.8 °. The arrangement and conformation of the substituents on the pyrazole ring are discussed. A pseudo plane of symmetry through the erythrofuranosyl moiety is present.
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry
The six-coordinated Sn is surrounded by two C at ~ 2.1 A and four S atoms, two of which are at ~ ... more The six-coordinated Sn is surrounded by two C at ~ 2.1 A and four S atoms, two of which are at ~ 2.5 A and two at .~ 3.2 A. With the two C and the two S atoms at ~2-5 A a deformed tetrahedron with approximate mm2 symmetry is observed. When the two remaining S atoms at ~3-2 A are added, the coordination sphere is a strongly distorted octahedron.
Mitteilungen Aus Lebensmitteluntersuchung Und Hygiene, 2003
Thèse de Doctorat à l'Université de Genève, 1971
Le système luminescent H3BO3 / 2 - hydroxy - 4 - methoxy - 4’chloro - benzophenone (HMCB) / H2SO4... more Le système luminescent H3BO3 / 2 - hydroxy - 4 - methoxy - 4’chloro - benzophenone (HMCB) / H2SO4 conc. a d’abord été étudié par la méthode des variations continues mettant en évidence les complexes A1R2 et A2R2 . L’application d’autres méthodes faisant varier alternativement le ligand et l’atome central ont ensuite mis en évidence les complexes A1R1, A1R2 et A2R2 et leurs constantes globales apparentes ( β(ij) ) et coefficients d’efficacité apparents (ϕ(ij)). Un complexe solide de type A2R2 a aussi pu être isolé et analysé, présentant un noyau central à six atomes de B (2x), de S (1x) et d’O (3x), lié à deux réactifs (HMCB). Un schéma de réactions a ainsi pu être établi confirmant l’hypothèse de Langmyhr et Arnesen(32) selon laquelle H3BO3 peut former dans H2SO4 conc. avec certains réactifs des complexes de type A2R2 similaire à celui identifié ici. Pour pouvoir appliquer la méthode fluorimétrique à l’HMCB au dosage de traces de B en milieu H2SO4 conc. aux eaux, sols et plantes il a d’abord fallu éliminer les matières organiques et les traces de fluorescences résiduelles gênantes. Pour cela une minéralisation par voie humide par adjonction lors du chauffage, de gouttes de H2O2 (30%) à 3 ml de H2SO4 conc. a été développée. L’interférence d’ions métalliques est négligeable, celle de F- est faible et celle de NO3- et H2O2 peut être éliminée. Avec l’HMCB des nanogrammes de bore ont ainsi pu être dosés dans de nombreux très petits échantillons d’eaux, d’extraits de sols, d’humus et de plantes, avec des erreurs relatives (E%) ≤ à 10%. Il est d’un intérêt très spécial que avec l’application de la méthode à l’HMCB à des extraits d’humus solides et légers de différents sols Français, obtenus selon la méthode de Hardisson et al., des quantités de B de l’ordre de 10 ppm ont été trouvées. Ces fractions de l’humus fortement liées au bore pourraient même être une caractéristique essentielle des sols.
The luminescent system H3BO3 / 2 - hydroxyl - 4 - methoxy - 4’chloro - benzophenone (HMCB) / H2SO4 conc. was first studied by the method of the continuous variations to identify the complexes A1R2 and A2R2. Then further methods, based on the alternative variations of the ligand and the central atom, gave a more detailed view of the system and identified the complexes A1R1, A1R2 et A2R2 and their apparent global constants (β(ij) ) and apparent efficiency coefficients (ϕ(ij)). Also, a solid complex of the type A2R2 was isolated and analyzed, presenting a central hexagonal ring with the atoms: B (2x), S (1x) and O (3x), bound to two reagents (HMCB). A scheme of reactions could be established and the hypothesis of Langmyhr et Arnesen(32) confirmed, that H3BO3 can form in H2SO4 conc. with certain reagents, complexes of a A2R2 type similar to the one identified here. To be able to apply the fluorimetric HMCB method to determine traces of B in H2SO4 conc. in water, soils and plants it was necessary to eliminate the organic matter and traces of the residual fluorescence. A mineralization with addition of drops of H2O2 (30%), during the heating, to 3 ml of H2SO4 conc. was so developed. The interferences with metallic ions is negligible, the one of F- is low and that of NO3- and H2O2 can be canceled. So with this method it was possible to determine nanograms of boron in numerous very small samples of water, soil extracts, humus and plants with an relative errors (E%) ≤ to 10%. It is of outstanding interest that with the application of this method to the solid and light humus extracts of different French soils, obtained by extractions and concentrations according to Hardisson et al., quantities of B of the order of 10 ppm were found. These humus fractions strongly bound to boron, may well be an essential characteristic of soils
The crystal structure, including H positions, of the monoclinic zeolite mineral parthéite (space ... more The crystal structure, including H positions, of the monoclinic zeolite mineral parthéite (space group C2/c) of framework type-PAR from Denezhkin Kamen (Urals, Russia) was refined, from single-crystal X-ray data to R 1 = 3.46%. In addition, in situ single-crystal X-ray data have been measured in steps of 25 °C up to 375 °C to analyze dehydration behavior. In situ Raman spectra of the natural (room temperature) and partly dehydrated varieties of parthéite have been recorded at 100, 150, and 275 °C. The structure of parthéite, Ca 2 Al 4 Si 4 O 15 (OH) 2 ⋅4H 2 O, is characterized by a tetrahedral framework interrupted by an OH-group forming the apex of one AlO 4 tetrahedron. In addition, this OH-group coordinates extraframework Ca together with two H 2 O molecules and four framework oxygen sites. The structure has four strong hydrogen bonds with H•••O interactions below 2 Å. The fifth hydrogen associated with a H 2 O molecule, exhibits two potential acceptors of weak hydrogen bonds with H•••O distances of ca. 2.5 Å. This softly bound H 2 O molecule is released at 150 °C without severe impact on framework distortions but with decrease of Ca coordination from seven to six. Concurrently with loss of the second H 2 O molecule at 250 °C, the structure further compacts and becomes severely distorted. The space group C2/c and the tetrahedral connectivity are preserved but β changes from 91 to 79° and the volume drops from 1730 to 1600 Å 3. Ca is still six-coordinated by five framework O atoms and OH.
Compte rendu des séances de la Société de physique et d'histoire naturelle de Genève, 1980
Séance du 8 mai 1980 Une nouvelle variété de péridot de la série forstérite-téphroïte, de composi... more Séance du 8 mai 1980 Une nouvelle variété de péridot de la série forstérite-téphroïte, de composition Fo 60-Tp 40 •
Compte rendu des séances de la Société de physique et d'histoire naturelle de Genève, 1980
Bulltin suisse Minéral. Pétrogr., 1977
Chantalite, CaA]2Si04(OH)4, occurs with vuagnatite, prehnite, hydrogrossular, chlorite and calci... more Chantalite, CaA]2Si04(OH)4, occurs with vuagnatite, prehnite, hydrogrossular, chlorite
and calcite in rodingitic dykes from an ophiolitic zone in the Taurus Mountains,
southwest Turkey. The name is for Mrs. Chantal Sarp. Both name and mineral have been approved by the Commission on new Minerals and Mineral Names of the
International Mineralogical Association.
Electron microprobe analysis has shown the uniform distribution of the major
elements and the absence of other components. X-ray powder diffraction data are from a Gandolfi camera. The crystal system is tetragonal, and the cell parameters are: a 4.945 (3), c 23.27 (2) A. The probable space group is I4i/a. The major X-ray diffraction lines occur at 5.810, 4.828, 4.171, 3.349, 2.598, 2.235, 2.202, 1.749, 1.529, 1.453 and 1.301 A. Crystals are always anhedral, varying in size between 0.1 and 0.3 mm. The measured density is 2.8-2.9 g/cm3, the calculated densitiy being 2.97 g/cm3. The difference is due to difficulties in getting material free of inclusions. The refractive
indices are: o> 1.653, e= 1.642, optically negative. The crystallization of chantalite is
related to metasomatic processes of rodingitization.
Schweiz, mineralogische petrographische Mitteilungen, 1985
Defernite, a new mineral with an unusual structure is orthorhombic: Pnam, a= 17.860 (5), b 22.7... more Defernite, a new mineral with an unusual structure is orthorhombic: Pnam,
a= 17.860 (5), b 22.775 (6) and c 3.658 (1) Â. V 1487.9 Â2, Z 4, Dx 2.42, Dm 2.5 g/cm3. The structure was solved by direct methods and the use of the Fourier difference map. From the counter diffractometer data, the structure was refined isotropically to a final
Rw of 0.082, whereas the final R( was 0.142. Probably the refinement could not be persued further due to the quality of the crystal and because the structure of the mineral contains weakly bound water molecules difficult to locate and shows occasional replacement of (C03)2 or (OH)"1. In relation to the structure the difficulty of the analysis of a carbonate mineral by microprobe is discussed. The structure is formed along axis a, of ribbons, composed of CaOy (OH)x polyhedra surrounding the (C03)"2 groups and along axis c, of and along axis c, of infinite channels in which water molecules could be located.
Keywords .-Defernite, structure.
Mitteilungen aus Lebensmitteluntersuchung und Hygiene, 2003
Les contractions de volume des melanges des alcools monohydroxyles, methanol, 1- et 2-propanol et... more Les contractions de volume des melanges des alcools monohydroxyles, methanol, 1- et 2-propanol et tert-butanol, avec l'eau sont determinees ici en utilisant des methodes semblables a celles developpees dans nos etudes precedentes pour les melanges ethanol-eau. On obtient pour chacun des melanges alcool-eau des courbes de contractions, representees en fonction des %mas, %vol et %mol, caracteristiques en ce qui concerne leurs intensites et formes. En passant du methanol, 1- et 2-propanol au tert-butanol, on observe des courbes dont les maxima vont de 12 a 40 %mol, de 34 a 55 %mas et de 42 a 62 %vol. L'intensite des maxima des contractions variera aussi de maniere differente selon le genre d'alcool et la temperature. Ainsi, si pour le melange methanol-eau les variations des contractions en fonction de la temperature sont a peine perceptibles, pour les melanges des autres alcools elles sont tres nettement marquees. Les maxima des contractions donnees en fonction des %mol données en fonction des % donnent de précieuses indications sur la nature des associations entre les molécules d'alcoolet d'eau Avec l'aide de la méthode de Jobles rapports moléculaires i/j les plus probables dans les mélanges alcool / eau ont ainsi été déterminésA2W3 pour le méthanol, A1W5 pour le 2-propanol, A1W6 pour le 1-propanol et A1W7 pour le ter-butanol. Comme visiblement on trouve dans ces mélanges des association de type "cluster", la formation d'agrégats encore plus complexes de type ( AiWj) est aussi possible..
The wallpaper-type crystal structure of wightmanite, Mg5(BO3)O(OH)5·1–2H2O, has been reanalyzed i... more The wallpaper-type crystal structure of wightmanite, Mg5(BO3)O(OH)5·1–2H2O, has been reanalyzed in order to better understand the position and bonding of hydrogen atoms. Single-crystal structure refinement yielded the monoclinic I2/m unit cell a = 13.5165(18), b = 3.0981(3), c = 18.170(3)Å, ß = 91.441(6)°, and V = 760.65(17)Å3, Z = 4. Hydrogen atoms of OH groups pointing to the inside of the elliptical channels oriented parallel to [010] are arranged in the form of two overlying, a–c parallel planar pentagons. The two pentagons point in opposite directions. Hydrogen-bond analysis shows that the hydroxyl groups are linked by complex polyfurcated, intra-molecular hydrogen bonds forming a web-like network coating the walls of the channels. The longest distance between hydrogens (7.226 Å) is observed in the pentagonal planes of the channel. The anisotropically refined oxygen atoms of the zeolitic water show their strongest vibration parallel to the b axis and in the direction of the lar...
American Mineralogist, 2012
ABSTRACT The crystal structure, including H positions, of the monoclinic zeolite mineral parthéit... more ABSTRACT The crystal structure, including H positions, of the monoclinic zeolite mineral parthéite (space group C2/c) of framework type -PAR from Denezhkin Kamen (Urals, Russia) was refined, from single-crystal X‑ray data to R1 = 3.46%. In addition, in situ single-crystal X‑ray data have been measured in steps of 25 °C up to 375 °C to analyze dehydration behavior. In situ Raman spectra of the natural (room temperature) and partly dehydrated varieties of parthéite have been recorded at 100, 150, and 275 °C. The structure of parthéite, Ca2Al4Si4O15(OH)2⋅4H2O, is characterized by a tetrahedral framework interrupted by an OH-group forming the apex of one AlO4 tetrahedron. In addition, this OH-group coordinates extraframework Ca together with two H2O molecules and four framework oxygen sites. The structure has four strong hydrogen bonds with H···O interactions below 2 Å. The fifth hydrogen associated with a H2O molecule, exhibits two potential acceptors of weak hydrogen bonds with H···O distances of ca. 2.5 Å. This softly bound H2O molecule is released at 150 °C without severe impact on framework distortions but with decrease of Ca coordination from seven to six. Concurrently with loss of the second H2O molecule at 250 °C, the structure further compacts and becomes severely distorted. The space group C2/c and the tetrahedral connectivity are preserved but β changes from 91 to 79° and the volume drops from 1730 to 1600 Å3. Ca is still six-coordinated by five framework O atoms and OH.
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry
R= 0.051 for 937 reflexions measured at room temperature (20°C). An intramolecular asymmetrical h... more R= 0.051 for 937 reflexions measured at room temperature (20°C). An intramolecular asymmetrical hydrogen bond with O(1)-O(2)=2.55 A, is present. in Table 1, were refined by full-matrix least-squares calculation, the function minimized being ~co(AF2o) where co= 1/a2(Fo) (ORXFLS3 programme by Busing et al., 1971b). A list of structure factors is available.* * This table has been deposited with the British Library Lending Division as Supplementary Publication No. SUP 30539 (26 pp., 1 microfiche). Copies may be obtained through The
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry
Counter technique, direct methods, least-squares refinement, R=5.0% for 1268 reflexions measured ... more Counter technique, direct methods, least-squares refinement, R=5.0% for 1268 reflexions measured at 20°C (R~=2.5 %). An asymmetrical hydrogen bond with O(1)...O(2) 2.540 A is present. Comparison with 2-hydroxy-4-methoxybenzophenone (HMB) is made and similarities and differences discussed. HMB and HMCB are non-planar and in both cases the crystal is composed of pairs of centrosymmetrically related molecules. The short intermolecular CI...C1 distances for HMCB and the presence of pairs of molecules for both compounds are important features. The present results may also add to the knowledge of the optical filter effect of this family of substances.
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry
Counter technique, direct methods, least-squares refinement, R=6.2% (Rw=2"2%) for 1258 reflexions... more Counter technique, direct methods, least-squares refinement, R=6.2% (Rw=2"2%) for 1258 reflexions measured at 20°C. The C-nucleoside CPOP is of interest as an analogue of pyrazomycin, an antitumour and antiviral antibiotic. In this fl-anomer, the erythrofuranosyl moiety is found in an unusual conformation with a torsion angle N(2)-C(1)-C(I')-O(I') [X] equal to 122.8 °. The arrangement and conformation of the substituents on the pyrazole ring are discussed. A pseudo plane of symmetry through the erythrofuranosyl moiety is present.
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry
The six-coordinated Sn is surrounded by two C at ~ 2.1 A and four S atoms, two of which are at ~ ... more The six-coordinated Sn is surrounded by two C at ~ 2.1 A and four S atoms, two of which are at ~ 2.5 A and two at .~ 3.2 A. With the two C and the two S atoms at ~2-5 A a deformed tetrahedron with approximate mm2 symmetry is observed. When the two remaining S atoms at ~3-2 A are added, the coordination sphere is a strongly distorted octahedron.
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