scholarly journals The crystalline structure of benzene

In a previous communication the writer gave the preliminary results of an investigation on the structure of solid benzene. It may be recalled that the unit cell was found to have the following dimensions at —22° C. ; a = 7·44, b = 9·65, c = 6·81 Å. U., while the space-group was determined as Q h 15 (orthorhombic bipyramidal). The unit cell contains four molecules, the molecules being centro-symmetrical. Since the publication of these results a certain amount of information has been obtained by other investigators. Bruni and Natta took powder photographs of benzene which confirmed the above values of the cell-dimensions; this is very satisfactory, since previous workers (Broomé and Eastman) had obtained axial ratios which did not agree particularly well with each other’s or with the writer’s. Mrs. Lonsdale has shown that in hexamethylbenzene the benzene ring is planar, the diameter of the atoms being 1·42 Å. U. More recently she has examined hexachlorobenzene, and although in this case the investigation did not yield quite such definite results, it was shown that if the ring is planar then again the diameter of the atoms must be 1·42 Å. U.

1996 ◽  
Vol 11 (4) ◽  
pp. 301-304
Author(s):  
Héctor Novoa de Armas ◽  
Rolando González Hernández ◽  
José Antonio Henao Martínez ◽  
Ramón Poméz Hernández

p-nitrophenol, C6H5NO3, and disophenol, C6H3I2NO3, have been investigated by means of X-ray powder diffraction. The unit cell dimensions were determined from diffractometer methods, using monochromatic CuKα1 radiation, and evaluated by indexing programs. The monoclinic cell found for p-nitrophenol was a=6.159(2) Å, b=8.890(2) Å, c=11.770(2) Å, β=103.04(2)°, Z=4, space group P21 or P2l/m, Dx=1.469 Mg/m3. The monoclinic cell found for disophenol has the dimensions a=8.886(1) Å, b=14.088(2) Å, c=8.521(1) Å, β=91.11(1)°, Z=4, space group P2, P2, Pm or P2/m, Dx=2.438 Mg/m3.


Nature ◽  
1956 ◽  
Vol 178 (4529) ◽  
pp. 379-379 ◽  
Author(s):  
K. HOOGSTEEN

1992 ◽  
Vol 47 (2) ◽  
pp. 263-274 ◽  
Author(s):  
Dietrich Mootz ◽  
Dieter Stäben

The melting diagram of the system tetramethylammonium hydroxide-water has been reinvestigated in the region of 66.67 - 100 mol% H2O , using DTA , DSC and temperature-dependent X-ray powder diffraction. This was done as correction and supplementation of a previous study in the same laboratory (D. Mootz, R. Seidel, J. Incl. Phenom. 8 , 139 (1990)). The system is now considered to contain as many as eight stable hydrates, three of them dimorphic with a low-temperature α and a high-temperature β form. The compositions are Me4NOH · χH2O with χ = 2 (α and β), 4, 4.6 (α and β), 5 (α and β), 6.67, 7.5, 8.75 and 10. A second 7.5-hydrate, called 7 .5 α in the previous study, is now regarded as metastable. - Structure determinations have been performed for the new phases with x = 4.6 (α), 6.67 and 8.75. The 4.6 α-hydrate, transforming to 4.6 β at 32 °C, is cubic with space group Pa3̄ and Z = 40 formula units per unit cell. The lattice constant is a = 21.493 Å at -160 °C. The 6.67-hydrate, melting with decomposition at 13 °C, is monoclinic with space group P21/m and Z = 6 . It was studied as the O-deuterated isotype with unit-cell dimensions a = 11.874, b = 20.019, c = 8.272 Å and β = 103.84° at 3 °C. The 8.75-hydrate, melting with decomposition at - 3 °C, is cubic with space group 14̄3 d, Z = 16 and a = 18.38(2) Å at - 20 °C. The three structures, as most others of the higher hydrates of the system studied previously, are those of polyhedral clathrate hydrates. For the hydrates 4 .6 α and 6.67 deviations of the anionic, i.e. proton-deficient, new water structures from being fully four-connected are described in detail. The 8.75-hydrate is isostructural with the hitherto unparalleled 9.75-hydrate of t-butyl amine. - The phase identity and structure of the 4.6 β-hydrate were recognized as those attributed to an erroneously assumed 5 β-phase in the previous study. 5 β now denotes the room-temperature form of the pentahydrate, previously called 5 α. The present 5 α is another of the new phases and the only one of the system with its structure still undetermined.


1999 ◽  
Vol 55 (2) ◽  
pp. 539-541
Author(s):  
Palangpon Kongsaeree ◽  
Jun Liang ◽  
Roy A. Jensen ◽  
Jon Clardy

The title protein has been crystallized in a new crystal form. The crystals belong to the cubic space group P4132 (or P4332) with unit-cell dimensions a = b = c = 126.1 Å at 100 K and typically diffract beyond 1.6 Å at the Cornell High Energy Synchotron Source (CHESS) A1 beamline.


1979 ◽  
Vol 181 (2) ◽  
pp. 497-499 ◽  
Author(s):  
R Aschaffenburg ◽  
D C Phillips ◽  
D R Rose ◽  
B J Sutton ◽  
S K Dower ◽  
...  

The Fv fragment of mouse myeloma protein M313 was crystallized from poly(ethylene glycol) solution in the form of monoclinic crystals, space group C2 and unit cell dimensions a = 5.96 nm (59.6 A), b = 5.66 nm (56.6 A), c = 13.79 nm (13.9 A) and beta = 99.7 degrees. Some unusual effects of poly(ethylene glycol)on protein crystals were noted and are discussed.


1981 ◽  
Vol 36 (2) ◽  
pp. 135-137 ◽  
Author(s):  
Evamarie Hey ◽  
Ulrich Müller

The crystal structure of [MePh3P]2TiCl6 was determined from X-ray diffraction data and refined to a residual index of R = 0.065. It crystallizes in the space group P2i/n with two formula units per unit cell; the cell dimensions are a - 921, b = 1314, c = 1648 pm and y - 100.87°. The TiCl62- ion occupies an inversion center and has the shape of a slightly distorted octahedron with Ti-Cl distances between 233 and 235 pm.


1976 ◽  
Vol 54 (17) ◽  
pp. 2723-2732 ◽  
Author(s):  
Simon E. V. Phillips ◽  
James Trotter

The structures of the title compounds have been determined by three dimensional X-ray crystal structure analysis.Crystals of anhydrous phenacylkojate are monoclinic, space group P21/c, with unit cell dimensions a = 9.087(4), b = 11.764(3), c = 12.714(4) Å, β = 116.57(2)°, Z = 4. The structure was solved by direct methods and refined by full-matrix least-squares to R = 0.044 for 1225 independent diffractometer observations. The crystal structure is held together by hydrogen bonding between carbonyl and hydroxyl groups and [Formula: see text] interactions.Crystals of the sodium chloride complex are monoclinic, space group C2/c, with unit cell dimensions a = 11.3714(6), b = 15.796(1), c = 14.487(1) Å, β = 97.241(5)°, Z = 4. The structure was solved by heavy atom and Fourier methods and comparison with the previously determined structure of the potassium iodide complex. It was refined to R = 0.040 for 1670 independent diffractometer observations. The structure closely resembles that of the potassium iodide complex (P21/n), but in C2/c, the alkali metal ion being eight co-ordinate in each. Na+—O distances are in the range 2.558–2.674 Å and the [Formula: see text] hydrogen bonded distance is 3.266 Å.


Sign in / Sign up

Export Citation Format

Share Document