Crystal data complex salts

The fact that tantalum and niobium complexes form in fluoride solutions not only supplements fundamental data on the coordination chemistry of fluoride compounds, but also has a broad practical importance. This type of solution is widely used in the technology of tantalum and niobium compounds in raw material digestion, liquid-liquid extraction, precipitation and re-pulping of hydroxides, and in the crystallization and re-crystallization of K-salts and other complex fluoride compounds. 

A slight deficiency of CsF mixed with [Xe,F,i]+ -AuF,]-was heated under dry N, to 110 °C, at which temperature XeF, evolved. The XeF, displacement CsF -)- [Xe,F ]- [AuF,] ->- 2XeF, + CsAuF, was completed under vacuum, (the slight excess of xenon complex sublimed out of the reactor) and a pale yellow solid remained. X-Ray powder photographs established that CsAuF, is isomorphous with the other CsMF, noble metal salts. Crystal data CsAuF,i M = 443-9 rhombohedral, a — 5-24 i 0-01 A a = 96-5 0-3°, V = 141 A, 2=1, Z c = 5-22 g cm-. Space... 

The complex salts usually crystallize as platelets of a size up to 1 X 2 X 0.5 mm. They exhibit a layered structure and a characteristic twinning. Microscopic studies indicate that the morphology of the crystals essentially remains unchanged during polymerization (21). However, occasionally crystals can be found that exhibit a splitting or crack formation subsequent to y-irradiation. The good quality of the crystals of 2 allowed to determine their structure by single crystal x-ray diffraction. The crystal data are listed in Table II. 

A preparative and X-ray crystallographic survey (ill) of salts of hexa-thionic acid led to unit cell and space group data for two salts, the crystals of which are, in view of the rather unstable nature and poor crystallization power of hexathionates, surprisingly well developed and stable. One is a potassium barium double salt, and the other a cobalt complex salt. 

The sodium salt of this Wells-Dawson-derived sandwich polyoxoanion is a yellow crystalline solid that is soluble in water. It is characterized in solution by P NMR (9 mM solution in H2O, D2O in a capillary insert) one resonance for the distal P atoms at —11.1 ppm (Aj/]/2 = 70 Hz). In the solid state the compound always contains NaCl as it must be crystallized from aqueous NaCl solution. If NaBr is substituted for NaCl in the aqueous crystallization process, crystals of the compound still form but now contain NaBr in place of NaCl. This sandwich complex is characterized in the solid state by IR (2% KBr pellet, 1300-400 cm ) 1091(s), 1017(w), 951(s,sh), 917(m), 826(s), 757(s), 695(s), 630(m,sh), 526(w). The crystal data for Nai2[Fe 4(H20)2(P2Wi5056)2] -58H20... 

Crystal stmcture data are available for an indole—trinitroben2ene complex (2) and for the lithium and sodium salts in the presence of polyamine Ligands (3). The crystal stmcture of indole itself is evidendy disordered (4). Table 1 gives the and C-nmr assignments in CDCl (5). C-nmr assignments have been tabulated for many other indole derivatives (6). 

Crystal structure data are indispensable for the discussion of the conduction mechanism in the cation radical salts based on the unsymmetrical complexes. In 2002,... 

Alkaline metal salts of the complexes [BeL2]2 are relatively easy to obtain as crystals some structural data are given in Table XII. Deviations from the regular tetrahedral structure are most marked with... 

Once a suitable crystal is obtained and the X-ray diffraction data are collected, the calculation of the electron density map from the data has to overcome a hurdle inherent to X-ray analysis. The X-rays scattered by the electrons in the protein crystal are defined by their amplitudes and phases, but only the amplitude can be calculated from the intensity of the diffraction spot. Different methods have been developed in order to obtain the phase information. Two approaches, commonly applied in protein crystallography, should be mentioned here. In case the structure of a homologous protein or of a major component in a protein complex is already known, the phases can be obtained by molecular replacement. The other possibility requires further experimentation, since crystals and diffraction data of heavy atom derivatives of the native crystals are also needed. Heavy atoms may be introduced by covalent attachment to cystein residues of the protein prior to crystallization, by soaking of heavy metal salts into the crystal, or by incorporation of heavy atoms in amino acids (e.g., Se-methionine) prior to bacterial synthesis of the recombinant protein. Determination of the phases corresponding to the strongly scattering heavy atoms allows successive determination of all phases. This method is called isomorphous replacement. 

It is difficult to prepare stretched oriented fibres and such fibres may differ in their polymer chain conformation compared with the unstretched materials. Furthermore the quality of the single crystal X-ray data is poor and difficult to interpret. In contrast power X-ray data of relatively high quality may be obtained from polycrystalline polymer films. Lightfoot, Mehta and Bruce (1992) have obtained the first crystal structure of a polymer-salt complex, PEOjiNaClQ from powder X-ray data. Fig. 5.11(h). The structure is similar to the corresponding PEOjiNal structure, the PEO chains are wrapped around the Na ions with each Na ... 

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