Sulfur tetrafluoride structure

The difference between equatorial and axial positions determines the arrangement of bonding pairs and lone pairs around an atom with a steric number of 5. An example is provided by sulfur tetrafluoride, a colorless gas that has industrial uses as a potent fluorinating agent. The Lewis structure of SFq shows four S—F bonds and one lone pair of electrons on the sulfur atom. These five pairs of electrons are distributed in a trigonal bipyramid around the sulfur atom. 

We discovered another synthetic technique that involves the conversion by direct fluorination of hydrocarbon polyesters to perfluoropolyesters followed by treatment with sulfur tetrafluoride to produce new perfluoropolyethers.42 The first paper in this area ofreasearch reported that conversion of poly(2,2-dimethyl-1,3-propylene succinate) and poly( 1,4-butylene adipate) by using the direct fluorination to produce novel branched and linear perfluoropolyethers, respectively. The structures are shown in Figure 14.6. The second paper concerns the application of the direct fluorination technology base directed toward oligomers, diacids, diesters, and surfactants.43... 

The sulfur tetrafluoride molecule has a distorted trigonal bipyramid structure with point group C 2V. The four fluorine atoms occupy four corners of the bipyramid around the central sulfur atom the fifth position is occupied by a lone pair of electrons.4... 

The structural parameters of the sulfur tetrafluoride molecule correspond well with its observed chemical properties only two fluorine atoms are active in reactions carried out at temperatures not exceeding 300 C. 

The result of the reaction of sulfur tetrafluoride with alcohols strongly depends on the structure of the alcohol. Simple aliphatic alcohols, such as methanol, ethanol and propan-2-ol, give alkyl ethers as the main product with only small amounts of fluoroalkanes.41 42 Yields of fluorinated products increase with increasing acidity of the hydroxy group and, in general, the reaction is only synthetically useful with alcohols equally or more acidic than tropolone (p K, = 6.42). 

Fig. 6.4 Sulfur tetrafluoride. (a) Trigonal bipyramidal structure with equatorial lone pair, (b) Trigonal bipyramidal structure with axial lone pair, (c) Experimentally determined structure of sulfur tetrafluoride.

Fig. 6,11 Molecular structures of (a) sulfur tetrafluoride (b) thionyl tetrafluoride ...

Exercise 16-31 Work out reasonable mechanisms for the reactions of phosphorus pentachloride and sulfur tetrafluoride with carbonyl groups. Both phosphorus and sulfur can accommodate five or more) bonded atoms, and the structure of phosphorus pentachloride in the solid state is [PCI4 ] [PCl60]. 

A fluoride of composition SF4 is formed when fluorine diluted with nitrogen is passed over a film of sulfur at — 75°C in the absence of oxygen and moisture. Write the Lewis structure of sulfur tetrafluoride. 

To predict the shape of a sulfur tetrafluoride molecule, SF4, we first write its Lewis structure (29a) (recall Example 2.7). The molecule is an example of an AX4E species, with four atoms on the central S atom and one lone pair. According to Fig. 3.4, the five electron pairs adopt a trigonal bipyramidal arrangement. The lone pair occupies an equatorial location. The energy is lowered further if the atoms move away from the lone pair (29b). This shape (resembling a slightly bent seesaw) is the one found experimentally. 

Gas-Phase NMR Studies of Structural Exchange in Sulfur Tetrafluoride and Bullvalene... 

Sulfur tetrafluoride oxide is a colorless gas, mp -99.6°, bp -48.5°. Hydrolysis to S02F2 is rapid. This compound has a trigonal-bipyramidal structure with the... 

Diethylaminosulfur trifluoride gives results similar to those of the reaction of sulfur tetrafluoride with epoxides, but mixtures of geminal diduorides. vicinal difluorides and bis(2-lluoroalkyl) ethers are obtained in low to moderate yield, depending on the structure of the epoxide." ... 

Use Lewis structures to predict the molecular polarities for sulfur difluoride, sulfur tetrafluoride, and sulfur hexafluoride. 

The fluorination of perfluoroacyloxy arenes with sulfur tetrafluoride to the corresponding perfluoroalkoxy arenes affords access to a larger structural variety [18]. For less sensitive structures, this method can also be extended to the synthesis of alkyl perfluoroalkyl ethers [19] (Scheme 2.173). 

It is also possible to encounter a molecule that seems to have too many valence electrons. When that happens, we expand the valence shell of the central atom. Consider the Lewis structure for sulfur tetrafluoride SF4, for example, which contains thirty-four valence electrons. 

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