Anion complex notation

The dimension of cross-linking (e.g., 1-, 2-, or 3-dimensional), the extension (as applies to, e.g., the inosilicates), and the number of cross-linked elements (e.g., 2 for double layers or double chains) are identified by the anion complex notation as proposed by Liebau [16]. The symbol 2/< of the anion complex of the metal silicate hydrates describes the two-dimensional cross-linking of the silicon oxygen tetrahedra to tetrahedral sheets. Following an older model, one, two, three, and five tetrahedral sheets are connected to form the bulk layer of kanemite or makatite, ilerite, magadiite, and kenyaite. 

A necessary consequence of choosing a complex systems to study is the rather ciumsy notation required to specify adequately what is being described mathematically it is, in one sense, little more than bookkeeping Take M cations located at p °, p2°.., pM° = p0 and which are stationary and N anions initially located at rj°, r2°,... rjV° = r0 at a time, t°. At a later time, t, the anions have diffused to r. The initial distribution of anions is... 

In the modern version of Werner s notation, brackets are used in writing cations or anions, but the net charges of the ions are not shown. In the formula [Pt(NH3)( ]Cl4, the portion in brackets represents a positively charged coordination complex in which Pt coordinates six NH3 ligands. The brackets emphasize... 

Inorganic double or triple helices are formed by two or three ligand strands wrapped around linearly disposed metal ions [13], Among cyclic transition metal complexes, circular helicates [nJ cH [ ] "cH is a general notation characterizing circular helicates (cH) with n = number of metal ions and m = helicity (m = 2 for a double helix) have specific features and may be considered as toroidal helices [34]. There are two different kinds of circular helical systems. Some structures self-assemble from the metal ions and the ligands only in the presence of an anion, which could act as a template [34,35,64-67], whereas, in other cases, the circular helicates self-assemble from the metal ions and the ligands alone [68-70]. 

Here the narrow prescription of Chapter 1 is widened to deal with more chemically complex phases, in which the materials may contain mixtures of A, B and X ions as well as chemical defects. In these cases, using an ionic model, it is only necessary that the nominal charges balance to obtain a viable perovskite composition. In many instances these ions are distributed at random over the available sites, but for some simple ratios they can order to form phases with double or triple perovskite-type unit cells. The distribution and valence of these ordered or partly ordered cations and anions are often not totally apparent from difEraction studies, and they are often clarified by use of the bond valence sums derived from experimentally determined bond distances. Information on the bond valence method is given in Appendix A for readers unfamiliar with it Point defects also become significant in these materials. The standard Kroger- fink notation, used for labelling these defects, is outlined in Appendix B. 

The anion in K4 Pt4(S04)s can be written in the form Pt4(S04)4(S04)2/2l . What does this notation tell you about the solid state structure of the complex ... 

With metal complex equilibria, where formation rather than dissociation constants are employed (Chapter 5), the expression looks a little different because log p and not pp is the customary notation. For the formation of FeY" from Fe and EDTA anion, Y" , for example,... 

Occasionally, it is advantageous to add one further level of complexity to the calculation diffuse functions. Here, heavy atoms are given access to diffuse s- and p-type functions so that their more diffuse orbital regions are considered in calculations. This has relevance for supramolecular chemists interested in anion recognition as diffuse and polarizable orbitals associated with halides are likely to be involved in anion recognition and binding. In Pople notation, these basis sets are denoted by a -I- sign as in 6-311-l-G. ... 

Attempts to prepare binary iron nitrosyl complexes by treatment of Fe(CO)3Cl with AgPFs or AgBF4 lead to Fe(NO)3(ri -PF6) and Fe(NO)3(T -BF4) rather than salts containing naked [Fe(NO)3] ions the r notation indicates that the anions coordinate through the metal centre through one F atom. 

Sometimes, also the notation H Cit is used for it in the literature, when the hydrogen atom from hydroxyl group is involved in complexation reactions. There are no asymmetric carbon atoms in citric acid or in its anions, i.e. they are optically inactive. However, it is possible to make them asymmetrical by substitution of one of the hydrogen atoms in the methylene groups by another atom or group (the central carbon atom is prochiral). 

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