Anion configuration

That there is a relationship between the coordination number of the metal in crystalline halogenocuprates(I) and halogenoargentates(I) and the properties of the cation with which it is coprecipitated would now seem to be well established. The tuning of anionic configurations to cation properties reflects the versatility in coordination requirements not only of the metal but also of the ligands. Cation size would appear to be of prime importance for the determination of a particular metal(I) coordination number, the tendency to attainment of a higher coordina-... 

In general, given that symmetric bidentate, asymmetric bidentate, and even monodentate anion configurations are seen in the various lactoferrin structures, it seems likely that it is changes of this nature that are detected spectroscopically. 

The angular distributions of the scattered electrons also yield Information on the anion configuration, although they siay be useful In practice only if the molecular symmetry is high. 

Following the identification of the first crystalline pentaphosphate, Na3Mg2P50ig, several other salts, which include CsV2P50,6 and CsFejPsOjg, have now been identified. Various anion configurations have been found among these salts [15]. 

The cation-anion configurations in the isolated pair are highly salt-specific, and are difficult to predict by plausible arguments. The rationale is that a given ion has to maximize interactions with many atoms of the counterion. 

A controversially debated subject is the existence (or not) of neutral ion pairs, causing the low ionicity of some Ionic Liquids [3]. The liquid structures show that cations and anions interact with many counterions. Neutral cation-anion configurations, the correlated translational motions of which are responsible for the low electrical conductance, only exist on fast (subpicosecond) time scales [8, 9]. 

Iwahashi, T., Miyamae, T., Kanai, K., Seki, K., Kim, D. and Ouchi, Y, Anion configuration at the air/liquid interface of ionic liquid [bmim]OTf studied by sum-frequency generation spectroscopy, J. Phys. Chem. B 112,11936-11941 (2008). 

Andersson, S. and Jagner, S., Crystal structure of tetrapropylammonium dichlorocuprate(l) - conparison of anionic configurations in halocuprates(l) crystallizing with symmetrical tetraaUqrlammonium and related cations, Acta Chem. Scand.AAO (1), 52-57 (1986). 

Fig. 5.10. Geometries of the most stable cation, neutral, and anion configurations of pentamer cUid 9-mer [84, 419]...

Table 1.1 Binding energy (meV) relative to neutral ground state for the lowest state of each lanthanide and actinide anion configuration. The numbers in parentheses are the number of predicted bound states for that configuration...

To deal with complex mineralogical structures such as the silicates, Pauling introduced in 1928 several rules which are still widely used. The first of these, and the most important, stresses the formation about each cation of a coordinated anion polyhedron. Allowable anion configurations are determined from radius-ratio considerations, such as those discussed above for simple ionic solids. Although these are not really precise enough to account in exact detail for all the structures of simple ionic crystals, they still provide an excellent guide for understanding the structure of minerals such... 

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