Polyanionic compounds

Give example of a successful ISE for measuring a macromolecular polyanionic compound. 

Polyanionic compounds. Frequently, the M atoms lose all their valence electrons to the X atoms, i.e. no cation-cation bonds occur and no nonbonding electrons remain at the cations, fe(MM) = 0 and E = 0. Equation (13.5) then becomes ... 

Table 13.1 Examples of polyanionic compounds which have integral valence electron concentrations per anion atom...

Polyanionic Compounds that do not Fulfill the Octet Rule... 

The Gillespie-Nyholm rules usually can also be applied to other polyanionic compounds with hypervalent atoms. As an example, some polytellurides are depicted in Fig. 13.6. The Te

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The number of known polycationic compounds of main group elements is far less than that of polyanionic compounds. Examples include the chalcogen cations S]+, S]+, Se]o and Teg that are obtained when the elements react with Lewis acids under oxidizing conditions. The ions S]1, Sc]1 and Te] have a square structure that can be assumed to have a 6n electron system. 

Links between atoms serve to compensate for the lack of the electrons which are necessary to attain the electron configuration of the next noble gas in the periodic table. With a common electron pair between two atoms each of them gains one electron in its valence shell. As the two electrons link two centers , this is called a two-center two-electron bond or, for short, 2c2e bond. If, for an element, the number of available partner atoms of a different element is not sufficient to fill the valence shell, atoms of the same element combine with each other, as is the case for polyanionic compounds and for the numerous organic compounds. For the majority of polyanionic compounds a sufficient number of electrons is available to satisfy the demand for electrons with the aid of 2c2e bonds. Therefore, the generalized 8 —N rule is usually fulfilled for polyanionic compounds. 

Schols D, Pauwels R, Witvrouw M, Desmyter J, De Clercq E. Differential activity of polyanionic compounds and castanospermine against HIV replication and HIV-induced syncytium formation depending on virus strain and cell type. Antiviral Chem Chemother 1992 3 23-29. 

K4Ge4, can be described as a polyanionic compound (as a Zintl phase also) containing the ion Ge44. This tetrahedral ion can be considered a naked (that is without any ligands bounded to the vertices) tetrahedral cluster formed by a main group element (that is Ee = 5 3 = 5X4 = 20). The electron count, on the basis of the Ge valence electrons and of the ion charge results in Ee = 4 X 4 + 4 = 20. 

The number of known polycationic compounds of main group elements is far less than that of polyanionic compounds. Examples include the chalcogen cations S4 , S , Se" ... 

P. J. Swart, M. E. Kuipers, C. Smit, R. Pauwels, M. de Bethune, E. De Clercq, H. Huisman, and D. K. F. Meijer, Antiviral effects of milk proteins Acylation results in polyanionic compounds with potent activity against human immunodeficiency virus type 1 and 2 in vitro, AIDS Res. Hum. Retroviruses 72 769-775 (1996). 

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