Polyanion-containing

The new ternary compound SrMgSi2 shows a considerable disproportionation of the silicon atoms into terminal (lb)Si , bridging (2b)Si, and branching (3b)Si" species (Fig. 2b, [31]). As shown in figure 2b the whole polyanion contains a one dimensional planar chain of silicon atoms with syndiotactically arranged side chains [Si(Si3)] . The Si-Si distances vary somewhat between 235 and 249 pm, with the shortest distances between the side chain bridging atoms and those of the main backbone. 

Cai4Sii9 is an overlooked phase in the binary system with nearly an even number of (3b)- and (2b)-Si atoms per formula unit [31, 48]. It contains a novel two dimensional polyanion of silicon which is displayed in Fig. 6a. The central unit is a 3,3,3-barrelane Sin which is linked via six Si3 bridges to six neighboring barrelanes. The whole polyanion contains seven layers of silicon atoms and has a width of ca. 900 pm. The barrelane part is shown in Fig. 6b with its trigonal planar (3b)-silicon atoms. The calcium atoms are distributed not only between but also inside the layers. 

Different ionic groups on the polyelectrolytes show different binding capacities, thereby the PEC formation. PEC formation between a polycation- and a polyanion-containing carboxylic groups... 

Such reactions are described in terms similar to those that have been applied for consideration of polyion exchange reactions (6). A reaction with a participation of water-soluble nonstoichiometric IPECs comprising fluorescently labeled PMA anions as HPE and P4VPQ cations as GPE-quenchers was studied. On addition of polyanions containing sulfo- or sulfonate groups to these systems, a full transfer of GPE chains from IPEC particles onto polysulfo/sulfonate anions is observed, as illustrated by Scheme (10) ... 

Heteropolyatomic Zintl anions like the polyhomoatomic ones may also exist in solution. Actually, many heteronuclear compounds, which are not obtained as crystalline species, possibly due to the same causes discussed above for the homonuclear species, may be studied in solution. Multinuclear NMR spectroscopy has proved to be an excellent technique for such studies. Mixed polyanions containing atoms of the same group can apparently be prepared in solution practically in any proportion within the normal nuclearity range of the homonuclear species by dissolving the appropriate ternary alloys. Thus for instance, from sodium-thin-lead alloys in ethylenediamine solution the following series of cluster anions [SnxPb9 x] may be stabilized. 

Ingri, N. Equilibrium Studies of Polyanions Containing BUI, SUV, GelV and W, Swedish Chemical Journal, 75,199,1963. 

Asensio, J. A., Bonos, S., Gomez-Romero, R, Enhanced conductivity in polyanion-containing polybenzimidazoles. Improved materials for proton-exchange membranes and PEM fuel cells, Electrochem. Commun. 2003, 5, 967-972. 

A veryHarge polyanion condensed 36 times has been observed in a more acid medium (H /Mo= 1.8) [77] (Figure 4.23). It probably exists in small concentrations only. This polyanion contains two identical Mo is units each made up of a crown of 11 molybdenum atoms suiTOunding a M07 group in which two Mo... 

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