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X-ray Investigation of Some Plastic Crystals I. Structure and Rotation: Cyclopentanol and dl-Camphene

 

作者: JohnR. Green,   DonaldR. Wheeler,  

 

期刊: Molecular Crystals  (Taylor Available online 1969)
卷期: Volume 6, issue 1  

页码: 1-11

 

ISSN:0369-1152

 

年代: 1969

 

DOI:10.1080/15421406908082949

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

X-ray photographs have been made of the two rotational forms of solid cyclopentanol and of the rotational form of dl-camphene. At −30°C, cyclopentanol in rotational form I has a hexagonal structure with a = 5.877 Å and c = 1.607 Å and with two molecules per cell. Agreement with the observed intensities can be obtained by assuming that the molecules are located at (1/3, 2/3, 1/4) and (2/3, 1/3, 3/4) and that they are rotating with spherical symmetry about their centers of mass. At −56°C, cyclopentanol in rotational form II also has a hexagonal structure but with a = 10.1 Å and c = 9.49 Å and with six molecules per cell. Intensity ratios are used to find the ratios of molecular scattering factors for camphene at six temperatures between −83.1° and + 24.0°. A model in which the camphene molecules rotate about their centers of mass with spherical symmetry does not produce agreement with the observed results. A model in which the camphene molecules fluctuate randomly among the twelve positions that result from applying the minimum symmetry operations for the point group in cubic lattice (class 23 or T) can be used to obtain agreement with the observed ratios.

 

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