Effect of Fluorination on the Nuclei Environments

02/2Si0Hp2 species for instance, is unlikely because of the strong probability of forming HF with two adjacent F and OH ligands. Then the most probable formula for these new species are 03/2SiF2 and 02/2SiF3. 

NMR lines. The resonance at 5iso( F) = — 127ppm can be assigned to SiFs species 

Various [SiFs] octahedral and [0(4 n)/2SiFn] (1 n 3) tetrahedral species or even fivefold coordinated [04/2SiF] environments have been identified by NMR spectroscopy ( H, F, Si) and FTIR spectroscopy [11,15,25], Besides various fluorosilicate species previously observed in moderately fluorinated siUca such as 02/2SiF2, 03/2SiF and 04/2SiF, two unprecedented species have been evidenced for highly fluorinating conditions [71]. 

The F (8jso F= 143.5 ppm and 136.5 ppm) and Si (8iso Si= 124 ppm and — 132 ppm) NMR resonances of these two species have been tentatively assigned to 03/2SiF2 and 02/2SiF3 based on the relative intensities of F and NMR lines 

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