Structure cristalline du monochlorobenzéne à 393 K et 14,2 kbars: un affinement par groupe rigide

In situ crystallization and crystal structure determination of chlorobenzene

“…The first report [11] dates back to 1958 when S. G. Biswas determined the unit cell parameters (space group Pmmn, a = 13.72 Å, b = 11.32 Å, c = 7.75 Å, V = 1203.656 Å 3 , density = 1.225 g cm −3 ) from DebyeScherrer photographs of frozen chlorobenzene at 93 K. In 1971, the crystal structure of chlorobenzene was determined at high pressure (14.2 kbar, 392 K). The unit cell parameters were consistent with the earlier report (space group Pbcn, a = 13.32(9) Å, b = 11.08(3) Å, c = 7.00(3) Å, V = 1033Å 3 , density = 1.447 g cm −3 , Z = 8) [12]. Although detailed crystal structure parameters of chlorobenzene are not available yet, the crystal structures of several dichlorobenzene isomers have been reported [13−19].…”

Etude par diffraction X des structures cristallines du furanne à la pression atmosphérique

“…Auparavant, le module r6sultant de l'6tude radiocristallographique de la phase II (d6crit plus loin) a 6t6 substitu6 g celui de Bak et al (1955); cette op6ration abaisselavaleur r&iduelle ~t 0,08. L'optimisation, au sens des moindres carr6s, des quatre parambtres variables trouv6s pr6c6-dement, a 6t6 effectu6e ~ l'aide du programme ORION (Andr6, Renaud & Fourme, 1971), tous les facteurs de structure exp6rimentaux ayant 6t6 affect6s d'un poids identique. Les variations par rapport h la solution de d6part sont r6duites, la plus notable &ant une rotation du plan mol&ulaire autour de l'axe a de 0,4 °.…”

Comparison between structural analyses of plastic and brittle crystals

“…The thermal parameters introduced as the usual U o parameters were constrained according to the atomic site symmetry with the SHELX program (Sheldrick, 1976). The second procedure assumes that the adamantane molecule is a rigid group: ORION program (Andre, Fourme & Renaud, 1971). In this model, the thermal vibrations are described by the classical T, L, S tensors.…”