Spectra of ring silicates

Plyusnina, 1.1., 1961. Infrared spectra of ring silicates. III. Zh. Strukt. Khim. 2 330. 

Fig. 5.18. The Si L2 3 x-ray emission spectra of various silicates, as shown, and of quartz. In terms of structural silicate groups (1-7) are island silicates, (8-9) ring silicates, (10-U) single-chain silicates, (12-15) double-chain silicates, (16-19) sheet silicatesj (20-22) framework silicates (after Dikov et al., 1976 reproduced with the publisher s permission).

Taking into account the different possible orientations of the two oxolane rings, relative to the apical ligand, for the three compounds 82, 83 and 84, the existence of syn/syn isomers in addition to syn/anti and anti/anti isomers must be considered. Although there is some confusion in the literature [92,93,94,95,96,97] about the correct interpretation of the NMR data of silicate complexes, there is no doubt that the three above-mentioned compounds exist in solution. In O Fig. 19, Si and (DEPT-135) NMR spectra of 82 and 83 are shown. 

Figure 14. Raman spectra of silicate xerogel after a 24-h hold in air at 650 °C or after 24 h in air and 24 h in vacuum at 650 °C. Corresponding MAS 29Si NMR spectra indicated that after the vacuum treatment up to 40% of the silicon atoms were contained in three-membered rings. (Reproduced with permission from reference 99. Copyright 1990.)...

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