Zinc , crystal structure

Figure Bl.8.4. Two of the crystal structures first solved by W L Bragg. On the left is the stnicture of zincblende, ZnS. Each sulphur atom (large grey spheres) is surrounded by four zinc atoms (small black spheres) at the vertices of a regular tetrahedron, and each zinc atom is surrounded by four sulphur atoms. On the right is tire stnicture of sodium chloride. Each chlorine atom (grey spheres) is sunounded by six sodium atoms (black spheres) at the vertices of a regular octahedron, and each sodium atom is sunounded by six chlorine atoms.

Fairall, L., et al. The crystal structure of a two zinc finger peptide reveals an extension to the rules for zinc finger/DNA recognition. Nature 366 483-487, 1993. 

Pavletich, N.P., Pabo, C.O. Crystal structure of a five-finger GLI-DNA complex new perspectives on zinc fingers. Science 261 1701-1707, 1993. 

Diamond is an important commodity as a gemstone and as an industrial material and there are several excellent monographs on the science and technology of this material [3-5]. Diamond is most frequently found in a cubic form in which each carbon atom is linked to fom other carbon atoms by sp ct bonds in a strain-free tetrahedral array. Fig. 2A. The crystal stmcture is zinc blende type and the C-C bond length is 154 pm. Diamond also exists in an hexagonal form (Lonsdaleite) with a wurtzite crystal structure and a C-C bond length of 152 pm. The crystal density of both types of diamond is 3.52 g-cm. ... 

The predominantly ionic alkali metal sulfides M2S (Li, Na, K, Rb, Cs) adopt the antifluorite structure (p. 118) in which each S atom is surrounded by a cube of 8 M and each M by a tetrahedron of S. The alkaline earth sulfides MS (Mg, Ca, Sr, Ba) adopt the NaCl-type 6 6 structure (p. 242) as do many other monosulfides of rather less basic metals (M = Pb, Mn, La, Ce, Pr, Nd, Sm, Eu, Tb, Ho, Th, U, Pu). However, many metals in the later transition element groups show substantial trends to increasing covalency leading either to lower coordination numbers or to layer-lattice structures. Thus MS (Be, Zn, Cd, Hg) adopt the 4 4 zinc blende structure (p. 1210) and ZnS, CdS and MnS also crystallize in the 4 4 wurtzite modification (p. 1210). In both of these structures both M and S are tetrahedrally coordinated, whereas PtS, which also has 4 4... 

Figure 29.1 Crystal structures of ZnS. (a) Zinc blende, consisting of two, interpenetrating, cep lattices of Zn and S atoms displaced with respect to each other so that the atoms of each achieve 4-coordination (Zn-S = 235 pm) by occupying tetrahedral sites of the other lattice. The face-centred cube, characteristic of the cep lattice, can be seen — in this case composed of S atoms, but an extended diagram would reveal the same arrangement of Zn atoms. Note that if all the atoms of this structure were C, the structure would be that of diamond (p. 275). (b) Wurtzite. As with zinc blende, tetrahedral coordination of both Zn and S is achieved (Zn-S = 236 pm) but this time the interpenetrating lattices are hexagonal, rather than cubic, close-packed.

Fig. 3.24 X-ray crystal structure of the 131b-bipy zinc complex. [Denmark, S.E. O Connor, S.O. Wilson, S.R. Angew. Chem., int. Ed. Eng. 1998, 37, 1149. Reprinted with permission from Wiley-VCH ...

The most remarkable pentammine is the hydride [Rh(NH3)5H]2+ [91], produced by zinc (powder) reduction of the chloropentammine salt. It shows u(Rh-H) at 2079 cm-1 in the IR spectrum (of the sulphate) and the low-frequency hydride NMR resonance at S = -17.1 ppm as a doublet showing Rh-H coupling (14.5 Hz). Its crystal structure shows the pronounced rraus-influence of hydride, with the Rh-N bond tram to H some 0.17 A longer than the cis Rh-N bond (Figure 2.45) [92]. 

IR spectra, 2,469 protonation, 2, 465 zinc transport, 6, 672 Citric acid, fluoro-absolute configuration, 2, 478 Citric add, hydroxy-crystal structure, 2, 478 Clathrates amines, 2,25... 

Zinc crystallizes in the hexagonal close-packed system its electronic structure is 4s2 and the melting point is 693 K. Since the zinc dissolution takes place at potentials very close to ffa0 the differential capacitance curves in the region of Ea=c in pure surface-inactive electrolyte solutions (KC1, pH = 3.7) can be determined directly for the Zn(llJO) face only... 

The differing malleabilities of metals can be traced to their crystal structures. The crystal structure of a metal typically has slip planes, which are planes of atoms that under stress may slip or slide relative to one another. The slip planes of a ccp structure are the close-packed planes, and careful inspection of a unit cell shows that there are eight sets of slip planes in different directions. As a result, metals with cubic close-packed structures, such as copper, are malleable they can be easily bent, flattened, or pounded into shape. In contrast, a hexagonal close-packed structure has only one set of slip planes, and metals with hexagonal close packing, such as zinc or cadmium, tend to be relatively brittle. 

Because the metallic radii of the d-block elements are all similar, they can form an extensive range of alloys with one another with little distortion of the original crystal structure. An example is the copper-zinc alloy used for some copper coins. Because zinc atoms are nearly the same size as copper atoms and have simi-... 

Ziegler-Natta catalyst A stereospecific catalyst for polymerization reactions, consisting of titanium tetrachloride and triethylaluminum. zinc-blende structure A crystal structure in which the cations occupy half the tetrahedral holes in a nearly close packed cubic lattice of anions also known as sphalerite structure. 

Zinc crystallizes in a deformed A3 structure with large axial ratio, causing the six equatorial neighbors (at 2.660 A.) to be nearer than the six neighbors in adjacent planes (at 2.907 A.). The bond numbers are 0.54 and 0.21, respectively, leading to 72(1) = 1.249 A. 

Fig. 1.2 Crystal structures of the major sulfides (metal atoms are shown as smaller or black spheres) (A) galena (PbS) structure (rock salt) (B) sphalerite (ZnS) structure (zinc blende) (C) wurtzite (ZnS) strucmre (D) pyrite structure and the linkage of metal-sulfur octahedra along the c-axis direction in (/) pyrite (FeSa) and (//) marcasite (FeSa) (E) niccolite (NiAs) structure (F) coveUite (CuS) structure (layered). (Adapted from Vaughan DJ (2005) Sulphides. In Selley RC, Robin L, Cocks M, Plimer IR (eds.) Encyclopedia of Geology, MINERALS, Elsevier p 574 (doi 10.1016/B0-12-369396-9/00276-8))...

Nowacki, W. Silverman, J. N. (1961). Crystal structure of zinc hydroxychloride II, Zn5(OH)8Clj. IHjO. Zeitschrift fiir Kristallographie, Kristallgeometrie, Kristallphysik, Kristallchemie, 115, 21-51. 

Although native PDFs utilise Fe rather than Zn, the PDF metal-binding site is still very representative of a traditional zinc-metalloprotease [57], containing a conserved HEXXH motif. Crystal structures of the Fe ", Ni ", ... 

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