Crystal structure of metal

Table 21-IV shows some properties of the metals and their crystal forms. Since different crystal forms are involved in the series, trends in the properties are obscured. Figure 21-2 shows scale representations of the crystal structures of metallic beryllium, calcium, and barium.

Metals Crystallographic Data File (CRYSTMET). Toth Information Systems Inc., Ottawa, Canada. Electronic database of crystal structures of metals, intermetallic compounds and minerals. WWW.Tothcanada.com. 

Crystal Structures of Metal-Peptide Complexes Hans C. Freeman... 

Ito, T. The crystal structure of metal diethyldithiophosphates. II. Lead diethyldithio-phosphate. Acta cryst. B28, 1034 (1972). 

Various X-ray crystal structures of metal-ligand complexes provided evidence of the geometry of the complexes in the solid state, even though the structure of these complexes may differ in solution. The hrst crystal structure of a bis(oxazoline)-metal complex was determined in 1994 by Brown and co-workers. " This group crystallized and elucidated the structure of V,V-bis-[2-((45)-(methyl)-l,3-oxazoli-nyl)]methane-bi(ri ethene)rhodium(I), 18a, as depicted in Figure 9.3. The key features of this crystal structure include the C2-axis of symmetry, the axial positions of the methyl groups and the orientation of the ethene molecules, orthogonal to the complexation square plane. In 1995, Woodward and co-workers were able to crystallize and determine the structure of benzylbis(oxazoline) with ruthenium... 

The concept of close packing is particularly useful in describing the crystal structures of metals, most of which fall into one of three classes hexagonal close packed, cubic close packed (i.e., fee), and body-centered cubic (bcc). The bcc unit cell is shown in Fig. 4.8 its structure is not close packed. The stablest structures of metals under ambient conditions are summarized in Table 4.1. Notable omissions from Table 4.1, such as aluminum, tin, and manganese, reflect structures that are not so conveniently classified. The artificially produced radioactive element americium is interesting in that the close-packed sequence is ABAC..., while one form of polonium has... 

The crystal structures of metal complexes of dtric acid have also received much attention. In... 

Starting point for this paragraph is the electrical conduction of metals, a phenomenon with which everyone will be familiar. A simplified crystal structure of metals was already discussed in chapter 3, in the paragraph on Chemical bonds . In a metal, there is question of an electron cloud which moves between the metal ions. When the metal is connected... 

Fritz G, Mittl PR, Vasak M, Grutter MG, Heizmann CW. 2002. The crystal structure of metal-free human EF-hand protein S100A3 at 1.7-A resolution. J Biol Chem 277(36) 33092-33098. 

There are two types of objects in supramolecular chemistry supermolecules (i.e., well-defined discrete oligomolecular species that result from the inter-molecular association of a few components), and supramolecular arrays (i.e., polymolecular entities that result from the spontaneous association of a large, undefined number of components) (4, 5). Both are observed in some metal-xanthate structures to be described herein. The most frequent intermolecular forces leading to self-assembly in metal xanthates are so-called secondary bonds . The secondary bond concept has been introduced by Nathaniel W. Alcock to describe interactions between molecules that result in interatomic distances longer than covalent bonds and shorter than the sum of van der Waals radii (6). Secondary bonds [sometimes called soft-soft interactions (7)] are typical for heavier p-block elements and play an important role as bonding motifs in supramolecular organometallic chemistry (8). Other types of intermolecular forces (e.g., Ji- -ji stacking) are also observed in the crystal structures of metal xanthates. 

Figure 12.8 Crystal structure of metal hydride, TiFeH2.

Crystal structure of metal-organic framework MOF-5 constructed of Zn04 tetrahedra and carboxylate ligands. Background showing a scanning electron microscope picture of cubic MOF-5 crystals. 

The molecular structure of AA provides a few preferred bidentate metal-binding sites, which have been demonstrated in a few crystal structures of metal-ascorbate complexes. 

The crystal structures of metals are simple. Those of some minerals can be very complex, but usually have simpler structures that can be recognized within the more complex structure. The unit cell is a structural component that, when repeated in all... 

Two crystal structures of metal complexes of a,a-trehalose 133 are reported. Two Cd (tren) residues are chelated by the Glcp-02,03 and the Glcp-02, 03 diolato moieties, respectively, in the dinuclear complex 135 (O Fig. 29). As in free a,a-trehalose in the crystalline state, direct intramolecular hydrogen bonds are not found due to conformational restraints, but two sequences of the type 02 ---H-0 ---H-06 with a linking water molecule H2O" are observed (the reversed direction is found in free a,a-trehalose) [153]. Only one of the two Glcp-02,03-chelation sites of a, a -trehalose is chosen in a mononuclear complex with Ni-Me3tren, the iVA, iV -trimethyl analog of Ni-tren, in which no support by an intramolecular... 

As noted in section 6.2, when the material of interest is an intermetallic alloy, the solution of its crystal structure may be simplified because intermetallics often form series of isostructural compounds. In contrast to conventional inorganic and molecular compounds, stoichiometries of the majority of intermetallic phases are not restricted by normal valence and oxidation states of atoms and ions therefore, crystal structures of metallic alloy phases are conveniently coded using the classification suggested by W.B. Pearson. According to Pearson, each type of the crystal structure is assigned a specific code (symbol), which is constructed from three components as follows ... 

The crystal structures of metallic oxides include examples of all four main types, molecular, chain, layer, and 3D structures, though numerically the first three classes form a negligible fraction of the total number of oxides. The metals forming oxides with molecular, chain, or layer structures are distributed in an interesting way over the Periodic Table. 

After noting some suboxides which are peculiar to Rb and Cs we shall describe the crystal structures of metal oxides in groups in the following order M3O, M2O, MO, MO2, MO3, MO4 M2O3, M2OS, M2O7, M3O4, and miscellaneous oxides M O, . The remainder of the chapter is devoted to brief surveys of the oxides of certain metals which present points of special interest. 

FIG. 24.7. The crystal structures of metallic borides (a) close-packed metal layer in UBj (AIB2) with B in trigonal prism holes between layers, (b) metal layer in UB4 with positions of 6- and 8-coordination between layers, (c) metal layer in CaB (ThBg) structure, (d) the UB4... 

Few other crystal structures of metal dithiophosphonates have been reported. These include the trans isomers of the O-ethylphenyldithiophosphonates of palladium(II) and platinum(II), M[S2P(OEt)Ph]2 (M = Pd, Pt), along with a report of cis-trans isomerization of the planar palladium(II) complex.114 The crystal structures of palladium and platinum /nmv-bis[(7-methyl (4-methoxyphenyl)phosphonodithioato] complexes, M[S2P(OMe)C6H4OMe-p]2, (M = Pd and Pt) have also been reported.107,108... 

The number of SB complexes crystallographically characterized is very broad, however, comparatively only a limited number of crystal structures of metal-free SBs has been reported.8-15 In those cases in which the structures of both the metal-free SB and their complexes are available, a comparative analysis can be made to establish how the conformation of the ligand is affected upon coordination to a metal. Several representative examples have been selected for this chapter.16-19... 

An extended material of valence electron spatial correlations (VEC) had been analyzed (Schubert, 1964), when it became apparent that one correlation of valence electrons alone is not sufficient for the explanation of crystal structures of metallic phases. The outer core electrons had to be taken into consideration. This may best be seen from the crystal structure of indium (Fig. 4) The lattice matrix of In may be given in diagonal form ai = (4.59 4.59 4.95) A. The explicit lattice constants are needed for verification that the proposed VEC is acceptable. The VEC is aj = aAi(l, —1,0 1,1,0 0,0,3/2) and may be decomposed into the equations at = a j + a2 a2 = - aj + a2 a3 = 3 a3/2, which may be verified by means of Fig. 4. If a correlation lattice is inserted into a crystal structure, this does not mean that there are positions of increased electron density in the cell, it only gives the commensurability which is favorable energetically. It is easily verified that the number of valence electron places per cell is = 12 and is equal to the number of valence electrons in the cell given above = 12. The A1 type of the VEC had been inferred from the diamond struc-... 

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