Three-dimensional nets

No equations are known analogous to those for polyhedra and plane nets relating to the proportions of polygons (circuits) of different kinds. A different approach is therefore necessary if we wish to derive the basic 3D nets. 

Evidently the simplest unit that can form a 3D pattern is a single point forming 

Structural units for three-dimensional nets (see text). 

Three-dimensional nets (a)-(d), the four nets of Table 3.6. (e) ThSii net, and 

Two (3, 4)-connected 3D nets representing (a) the structure of Ge3N4, (b) the arrangement of Pt and 0 atoms in Na PtaOa (shaded and open circles respectively). 

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The structural features of most niobium oxychlorides known to-date are summarized in Table 6.1. The use of a combination of chloride and oxide hgands leads to compounds with unique structure types [41], characterized by a remarkable variety of cluster frameworks, ranging from discrete cluster units to chains, layers, and three-dimensional nets, some topologies of which are unprecedented in compounds containing octahedral clusters. Most of the niobium oxychlorides known to date have anisotropic structures (the exceptions are Cs2LuNb,5Cli70 and PbLusNbsClisOg). 

Class 1 Molecules, which may create a three-dimensional net of strong H-bondings H2O, polyols, aminoalcohols, oxy-acids, polyphenols, hydroxylamine etc. 

Han, S. and Smith, J.V. (1999) Enumeration of four-connected three-dimensional nets. 111. Conversion of edges of... 

As a consequence of this repulsion the MnFe-octahedra of these groups MnaFg are distorted, the Mn—F-distances are 3 x 2 16 A and 3 X 2 12 A resp. The latter values correspond to the Mn—F-distances in the nearly undistorted MnFe-octahedra of the structure, which share comers only and like in the cubic perovskites bring about the three-dimensional netting of the lattice. 

Even so, the attempts to enumerate all possible four-connected three-dimensional nets shows that the expansion of even such a simple bond graph as that of Si02 is far from trivial. A more profitable approach has been to list and describe those networks that are commonly found, or seem likely to be found, in nature (O Keeffe et al. 2000). Thus the more pragmatic terminology introduced by Liebau (1985, pp. 76ff.) is frequently used to describe the structures of minerals. 

Wells, A.F. (1977) Three-Dimensional Nets and Polyhedra, John Wiley and Sons, New York. 

Wells, A. F. 1977 Three-dimensional nets and polyhedra. New York Wiley. 

The measure of the cross-linking is determined by the gel fraction—the fraction of the polymer which, after irradiation, is not soluble any more in methyl ethyl ketone (MEK) due to the presence of two- and three-dimensional net. The gel fraction is denoted usually by g, and as a function of the absorbed dose is given usually by the Charlesby-Pinner equation17, relating the sol fraction, s9 with the dose ... 

The attractive interactions of each cation with a number of anions and vice versa result in a network of strong attractive forces that extend throughout the whole crystal. We can think of these as a three-dimensional net of attractive forces. Disrupting these forces requires a large amount of heat energy therefore, ionic compounds usually have... 

In guanine hydrochloride dihydrate [GUANCD] (Fig. 15.22), the hydrogen-bond structure is a three-dimensional net. The positive charge appears to be located on N(7). The Cl" is four-coordinated, and five-coordinated when the minor component from the N(2) amino group is included. One water molecule is three-coordinated, the other four-coordinated. 

A. F. Wells, Structural Inorganic Chemistry, 5th edn., Clarendon Press, Oxford, 1984 A. F. Wells, Three-Dimensional Nets and Polyhedra, John Wiley and Sons, New York, 1977. 

Figure 7.22 Three-dimensional nets (a) the cubic diamond structure (b) the net equivalent to (a) (c) the cubic zinc blende (sphalerite) structure (d) the net equivalent to (c), which is identical to that in (b) (e) the hexagonal wurtzite structure (f) the net equivalent to (e)...

Many ways of catching and destroying the nematodes have developed. Some fungi make adhesive three dimensional nets (Fig 5.12). The three dimensional net is covered with an adhesive. When a nematode come in contact with the adhesive... 

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