Fluorine-silicon bonds, lengths

Figure 8.10 Representation of the crystal structure of [Cs((if-PhMe)3(p-Fln N(SiMe3)2 3)]. ° Indium, caesium, nitrogen and silicon atoms are shown as black spheres, fluorine atoms are grey and carbon atoms are white. Selected bond lengths Inl-NI 2.121(3), lnl-N2 2.128(3), In1-N3 2.127(3), Inl-FI 2.065(2), Cs1-F1 2.777(2)A...

Since, as mentioned before, the hydrolytic stability of the silicon-fluorine bond is determined by the nature of the substituents on silicon, a theoretical model of organofluorosilane hydrolysis was developed by means of density functional theory (DFT) methods. As concluded by the authors (Hohne et al. 2009), the calculation of the difference of Si-F bond lengths between optimized structures of the starting material and the intermediate structure allows the... 

The variable-temperature NMR spectra of 3 and 4 were carefully analyzed and interpreted in terms of four different rate processes (Figure 3). For 3a the fastest rate process was the exchange between penta- and tetracoordinate silicon, i.e. the interchange of bond lengths between the bridging fluorine and each silicon atom (Fbr—Sii Fbr—Sia,... 

An X-ray crystallographic study for 170 revealed a slightly distorted octahedral geometry, as is expected for hexacoordination191. The four Si—F bonds in this compound are essentially equal in length, while the Si—N distance (2.213 A) is shorter than that found in the neutral pentacoordinate precursor (2.318 A), or in a previously reported neutral hexacoordinate difluorosilane, 174 (2.59, 2.81 A)194. The position of silicon in 170 is 0.16 A displaced from the mean plane defined by carbon and three fluorine ligands, away from the coordinated nitrogen191. 

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