Diffraction group table

Table II. Identification of the space group from the diffraction groups. Table from reference [3].

Table I. Identification of the diffraction group from the WP, BF, DF and +/g symmetries. Table from references [3] and [4],...

The connection between the diffraction group and the point group is obtained from Table II. High symmetry diffraction groups are very useful. One or a few Zone-Axis Patterns are required to identify the point group. 

As follows from Table 2.12, there are only two possible diffraction groups for the monoclinic C-centered lattice. The second diffraction group, Clcl, differs from the first one, C1-1, by the presence of /(O/reflections only with even 1. As is easy to see from Table 2.11, none of the Bragg peaks hQl with / = 2 + 1 is observed, or in other words, the allowed reflections condition is / = 2n for hOl (these are shown in bold). Other conditions are... 

Data collected in Table 3 illustrates these options showing how it is practically done in different electron-diffraction groups [134-165]. 

Similar reactions of P N=C=NPr with RuHX(CO)(PPhj)2 (X = Cl, Br) led, via insertion of the carbodiimide in the metal-hydride bond, to RuX(CO)(PPh3)2 CH2=C(Me)NC(H)NPr . A single crystal X-ray diffraction study of the chloro complex (21) showed the presence of a chelating formamidino group, while an isopropyl group has been converted to an isopropenyl group (Table 3). ... 

The relation between the diffraction groups and the crystal point groups can be seen in Table 3. 

Table 3. Relation between diffraction groups and crystal point groups (from Buxton et al [17])...

The indexing procedure we have just discussed has provided us with information on the unit cell, and thus the Bravais lattiee. Taking the symmetry of the diffraction pattern, the so-called Laue group (Table 10.1), into account, we ean now determine whieh reflections have to be measured, and which reflections are equivalent by symmetry. For instance. Table 10.1 shows that for the triclinic system the Laue group is 1, i.e. the diffraction pattern is centrosymmetrie and only half the reflections have to be examined for a monoclinie crystal the Laue group is 2/m, i.e. the diffraction pattern has two elements of two-fold symmetry and consequently only a quarter of the reflections are needed. In the monochnic case we have to measure all... 

Up to now, fifteen group 13-stibine R3AI—SbR and four group 13-bismuthine adducts R3AI—BiR3 have been structurally characterized by single crystal X-ray diffraction studies. Their central structural parameters are summarized in Table 5. Structures 1-4 show the solid state structures of four representative adducts. 

To better understand the differences in their catalytic behavior, the catalysts were characterized by XRD and UV-vis DRS. Unfortunately, except for the peak at 77.6° 26 (311 diffraction), the other Au diffraction peaks overlapped with those of y-Al203. The size of the coherent domains of Au, listed in Table I, were estimated using the width of this diffraction peak and the Debye-Sherrer equation. They showed that catalysts of both groups A and C had small coherent domains, whereas those of group B had large domains. 

X-ray diffraction technique M = microwave spectroscopy. Values in parentheses are the calculated geometries (see Table 1). Point group C2V... 

---