The crystal and molecular structures of adamantanecarboxylic acid at 173 and 280 K

1990 ◽  
Vol 68 (7) ◽  
pp. 1163-1169 ◽  
Author(s):  
Francine Bélanger-Gariépy ◽  
François Brisse ◽  
Pierre D. Harvey ◽  
Denis F. R. Gilson ◽  
Ian S. Butler
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
High Temperature Phase ◽  
Molecular Structures ◽  
Temperature Phase ◽  
Carboxylic Group ◽  
Disorder Transition ◽  
Text Type ◽  
Adamantanecarboxylic Acid ◽  
Unit Cells

The crystal structure of adamantanecarboxylic acid, tricyclo[3.3.1.13,7] decan-1-carboxylic acid C10H15COOH, has been determined by X-ray diffraction at two temperatures, 173 and 280 K. At both temperatures, the unit cells are triclinic, space group[Formula: see text], and each contains two molecules. At 173 K, a = 6.452(3), b = 6.681(2), c = 11.510(3) Å, α = 80.84(2)°, β = 87.22(3)°, γ = 74.11(3)°; V = 471.10 Å3, Dx = 1.271 g cm−3, [Formula: see text]. The structure was solved by direct-methods. The least-squares refinement, based on 1347 observed reflections converged to R = 0.0485 and Rw = 0.0415. At 280 K, a = 6.503(2), b = 6.849(2), c = 11.620(4) Å, α = 77.11(2)°, β = 85.77(2)°, γ = 76.34(2)°; V = 490.11 Å3, Dx = 1.221 g cm−3, [Formula: see text], R = 0.0874, and Rw = 0.0512 for 828 observed reflections. The low-temperature form is ordered while at room temperature the molecule is disordered. In the structure of the high-temperature phase, the adamantyl group takes two distinct orientations, in a 60:40 proportion, at about 14° from one another. The carboxylic group also has two orientations differing by about 170°. The geometry of the adamantane skeleton is not affected by the presence of the carboxylic group. The molecules form centrosymmetric dimers through hydrogen bonds of the [Formula: see text] type. The [Formula: see text] distances range between 2.616(11) and 2.752(15) Å. The order-disorder transition is interpreted using the Guthrie–McCullough approach. Keywords: adamantanecarboxylic acid, order–disorder transition, crystal structure.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

On the Phase Transition of Bis(pyridinium)hexachlorometallates, (C5H5NH)2[MCl6], M = Sn, Te, Pb, Pt. An X-Ray and 35Cl NQR Study

1987 ◽  
Vol 42 (7) ◽  
pp. 739-748 ◽  
Author(s):  
Dirk Borchers ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Phase Ii ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray ◽  
Lattice Constants ◽  
Pyridinium Ring ◽  
35Cl Nqr ◽  
Low Temperature Phase

A phase transition has been observed in bis(pyridinium) hexachlorometallates (C5H5NH)2[MIVCl6]. M = Sn. Te. Pb. Pt. The crystal structure of the low temperature phase II of the salt with M = Sn was determined, space group C 1ḷ- P 1̅, Z = 1 (a = 734.1pm, b = 799.0 pm, c = 799.7 pm,α= 83.229°. β = 65.377°, γ= 84.387°, T = 297 K). The four compounds are isotypic in phase II as well as in the high temperature phase I (C2H2-B2 /m, Z = 2) for which the crystal structure is known for M = Te . The lattice constants of all compounds (both phases) are given. The temperature dependence of the 35Cl NQR spectrum was investigated. The three line 35Cl NQR spectrum is in agreement with the crystal structure. The dynamics of the pyridinium ring shows up in a fade out of part of the 35Cl NQR spectrum . The influence o f H ↔ D exchange on 35Cl NQR is studied and an assignment of ν (35Cl) ↔ Cl(i) is proposed. The nature of the phase transition P1̅ (Z = 1) ↔ B2 /m (Z = 2) is discussed.

Raman and nuclear quadrupole resonance studies of the phase transition in pentachlorophenol

1978 ◽  
Vol 56 (3) ◽  
pp. 359-362 ◽  
Author(s):  
H. F. Shurvell ◽  
J. Korppi-Tommola ◽  
R. J. C. Brown
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
Liquid Nitrogen Temperature ◽  
High Temperature Phase ◽  
Complete Loss ◽  
Temperature Phase ◽  
Disordered Structure ◽  
External Mode ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Raman and nqr spectra of pentachlorophenol (PCP) have been recorded at temperatures above and below the transition at 62 + 2 °C. The complete loss of structure in the Raman external mode region and the disappearance of the 35Cl nuclear quadrupole resonances above the transition temperature indicate a disordered structure for the high temperature phase. Super-cooling is observed in nqr and Raman spectra when the sample is cooled through the transition temperature. No evidence for any new crystal phase is observed on cooling the sample to liquid nitrogen temperature. Eleven of the 12 external modes predicted from the reported crystal structure of PCP have been observed in the Raman spectrum at 77 K.

Experimental Investigations of the High-Temperature Phase Relationship and Ordering Transition in Ni-Mn-Ga Ternary System

2010 ◽  
Vol 148-149 ◽  
pp. 1695-1700
Author(s):  
Yun Qing Ma ◽  
Shui Yuan Yang ◽  
Ryosuke Kainuma ◽  
Kiyohito Ishida ◽  
Cui Ping Wang ◽  
...  
Keyword(s):  
Ternary System ◽  
Phase Relationship ◽  
Phase Region ◽  
High Temperature Phase ◽  
Experimental Investigations ◽  
Temperature Phase ◽  
Critical Temperatures ◽  
Disorder Transition ◽  
Mn Content ◽  
Ordering Transition

The phase equilibria at 900 °C and B2/L21 order-disorder transition in the Ni-Mn-Ga ternary system were investigated by analyzing the equilibrated alloys and diffusion couples using a combination of techniques. It was confirmed that a bcc single phase region exists in a wide composition range at 900 °C, and the critical temperatures of B2/L21 order-disorder transition were determined in Ni-50 at.% section, which exhibits a maximal ordering transition temperature of 796 at Mn content of 25 at.%. The obtained results will be helpful for the preparation and annealing of Ni-Mn-Ga alloys in the specific temperature.

Energetics of the oxygen vacancy order-disorder transition in Ba2In2O5

1993 ◽  
Vol 8 (7) ◽  
pp. 1484-1486 ◽  
Author(s):  
T.R.S. Prasanna ◽  
Alexandra Navrotsky
Keyword(s):  
High Temperature ◽  
Oxygen Vacancy ◽  
Configurational Entropy ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Disorder Transition ◽  
First Order ◽  
Enthalpy And Entropy ◽  
Entropy Of Transition

The heat capacity and the enthalpy associated with the reported oxygen vacancy order-disorder transition in Ba2In2O5 were measured by high temperature step scanning calorimetry. The transition temperature is 1205 ± 2 K. The transition appears first order or nearly so. The enthalpy and entropy of transition are 1.3 kJ/mol and 1.1 J/mol K, respectively. The latter is only 4.8% of the configurational entropy, arising from mixing one vacancy and five oxygens per formula unit, 22.5 J/mol K. This suggests that the transition involves only a small fraction of the oxygen vacancies and implies extensive short-range order, SRO, in the high temperature phase.

Superprotonic high temperature phase and refinement of the low temperature structure of CsHSeO4

2001 ◽  
Vol 216 (3) ◽  
Author(s):  
M. A. Zakharov ◽  
Sergej I. Troyanov ◽  
Erhard Kemnitz
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Low Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Superprotonic Phase

AbstractThe crystal structure of the high temperature superprotonic phase of CsHSeO

A new polymorph of Cd3B2O6: synthesis, crystal structure and phase transformation

RSC Advances ◽  
2014 ◽  
Vol 4 (25) ◽  
pp. 13195-13200 ◽  
Author(s):  
Xingwen Zhang ◽  
Hongwei Yu ◽  
Hongping Wu ◽  
Shilie Pan ◽  
Anqing Jiao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transformation ◽  
High Temperature ◽  
Transformation Process ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Phase Transformation Process

A new high-temperature phase of Cd3B2O6 (β-Cd3B2O6) has been discovered and the phase transformation process between α- and β-Cd3B2O6 was investigated.

Crystal Structure and Chemical Bonding of the High-Temperature Phase of AgN3.

ChemInform ◽  
2007 ◽  
Vol 38 (17) ◽  
Author(s):  
Carsten L. Schmidt ◽  
Robert Dinnebier ◽  
Ulrich Wedig ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Chemical Bonding ◽  
High Temperature Phase ◽  
Temperature Phase
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