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Topology diamond-like

To achieve non-zero 7ta—7tb conjugation, the pi NBOs of 18 may polarize in opposite directions, leading to a wavefunction of lower symmetry than the nuclear framework. Alternatively, the nuclear framework may distort to diamond-like D2h geometry. However, each such distortion destabilizes what is already a highly unfavorable Lewis-structure wavefunction, so cyclobutadiene is expected to remain highly destabilized relative to other possible polyene topologies. [Pg.202]

Some general points about interpenetrating networks can be illustrated by the example of Zn(CN)2, which was structurally characterized over half a century ago [3]. It consists of two independent diamond-like nets with the 66-a topology, in which zinc provides the tetrahedral nodes and cyanide provides linear connections between nodes. These two equivalent but independent nets interpenetrate as shown in Figure 4, such that the nodes of one net are located at the centers of the... [Pg.79]

Zn(n) [MT2]3(H20) 3-D super-diamond-like topological network Cubic Fdim 2.163-2.166 ... [Pg.332]

In addition a recent approach to structural description has been reported in which common structural types have been given a three letter designation relating the structure to a well-known solid-state, typically inorganic, compound [6]. For example the diamond-like net constructed from the connection of tetrahedral nodes has 66 topology but is simply described as dia, relating the structure directly... [Pg.205]

Figure 2 (a) A schematk representation of a diamond-like network formed from tetrahedral tetracations and linear dianions. The volume of the polycation and the length of the dianion will play a crucial role in determining the size of the nanometersized voids present in the network, (b) A schematic representation of electrostatic enforcement of anion networks by polycations. For convenience, the concept is portrayed in two-dimensional space. The topology of each cation is defined by the spatial arrangement of the individual cationic centers... [Pg.111]

Figure 8.12 Structure topology of the porous diamond-like frameworks with allg nyl and seleeted rings. ... Figure 8.12 Structure topology of the porous diamond-like frameworks with allg nyl and seleeted rings. ...
From these calculations, it is, therefore, fair to conclude that, taken both total energies and spectroscopic data into consideration, a Pandey ir-bonded chain topology is most likely to be the correct structure for the 2x1 phase of the (111) surfaces of diamond. Si, and Ge. [Pg.376]

Attempts at C[4]-supported cluster synthesis with first row TM ions under ambient conditions gave rise to the formation of two new assembly types. The first of these was found to be a family of mixed valence [Mn 2Mn 2(C[4])2(p3-OH)2(dmf)6] clusters (1, Fig. 25.3a), the metallic skeleton of which has a planar diamond- or butterfly-like topology (Fig. 25.4a) [22, 23]. The (Jahn-Teller distorted) Mn and (distorted octahedral) Mn ions occupy the wing-tip and body positions respectively and these are bridged via the C[4] lower-rim oxygens and p3-hydroxides. This cluster motif is not unusual in Mn cluster chemistry but, in this case, the oxidation states are reversed relative to those previously reported [24]. A notable feature of 1 is that the [Mn (C[4])] moiety caps the cluster core, a feature observed in all clusters ccmtaining manganese ions. [Pg.674]

The bulk diamond lattice can also be terminated between the layers of this bilayer, leaving three times as many dangling bonds to satisfy this can be accomplished by adding a trivalent adsorbate like As, Sb or Bi, which then forms a layer that substitutes for the outermost half of the more stable Si bilayer. A similar feature is part of the so-called honeycomb-chained-trimer (HCT) reconstruction due to several metal adsorbates. Here a lateral relaxation in the lower half of the bilayer leads to trimerization of those Si or Ge atoms. A related type of structure, called conjugate honeycomb-chained-trimer (CHCT) model, occurs for other metal adsorbates here it is the metal adatoms that trimerize instead of the substrate atoms we thus classify this as not reconstructed, since the Si-Si bonding topology is bulk-like. As Table 23 shows, a number of other reconstructions have been identified, many of which are quite complex. [Pg.65]


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See also in sourсe #XX -- [ Pg.102 ]




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Diamond-like

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