Network four-connected three-dimensional

Many of the four-connected three-dimensional networks have been tabulated by Smith (1988) and can be used to describe the materials based on silica. These... 

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. 

Crystalline semiconducting sulfide and selenide zeolite analogs were synthesized that possess four-connected, three-dimensional tetrahedral networks built from tetravalent... 

The carbon atoms in a diamond are connected in a three-dimensional network, each atom connected to four others. Each atom is at the center of a regular tetrahedron, as shown above. We describe this geometry, which occurs in many compounds of carbon, in Chapter 9. The three-dimensional connections result in a solid that is transparent, hard, and durable. The diamond structure forms naturally only at extremely high temperature and pressure, deep within the Earth. That s why diamonds are rare and precious. 

PSDVB copolymers and their ion exchange derivatives consist of a three dimensional four-connected network structure. Such networks may have a statistically isotropic structure that includes tetrahedral cells, such as the X" unit structure described by Flory (6). The four-connectedness results from the expected pairwise chain connecting function of... 

Three-dimensional network with chains of V06 distorted octahedra connected pairwise by an S04 group via comer sharing A V06 octahedron has four S04 tetrahedra in the equatorial plane... 

The basic structure of the hydrated oxalato complex, NaNpC CyiVSPkO, is made up of infinite chains of composition [Np02C2O4(H2O)]" connected by Na+ ions and H20 molecules in a three-dimensional network. The neptunium atom is at the centre of a pentagonal bipyramid, coordinated to four O atoms from two C204 groups and a fifth from the water molecule in the equatorial plane.17915... 

The topological structure of X- and Y-type zeolites (also known as faujasites) consists of an interconnected three-dimensional network of relatively large spherical cavities termed supercages (diameter of about 13 A Figure 12). Each supercage is connected tetrahedrally to four other super-... 

The macrocycle 131, containing a 2,6-dipicolyl fragment, has been used as a receptor for malate dianion in aqueous solution <2006CC1227>. 4-Aminopyridine coordinated to Ag(l) and hydrogen-bonded to nitrate forms a high-symmetry three- and four-connected hydrogen-bonded three-dimensional network <2006CC1082>. 

The network comprises W(IV) ions, which are connected to nearest neighbour Fe(II) ions through cyanide bridges in a three-dimensional grid-like arrangement. The Fe(II) ions are in an octahedral environment, bonded to four nearest neighbour W(IV) ions two axial water molecules complete the sixfold coordination. 

Generally, the formation of two-dimensionally linked assemblies affords subunits possessing either four-connected points or a combination of two three-connected points. Figure 18 illustrates the way in which two dimeric subunits may be combined to form a planar honeycomb network. 

In the random network theory of glass d, the atoms form a three-dimensional connected structure without periodic order and with energy content comparable to that of the corresponding crystalline material. The coordination number of an atom determines its role in a glass structure, and the fulfillment of four rules determines whether an oxide is to be a glass former ... 

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