Lithium-fluorine bond

Clearly the fluorine atom holds electrons much more strongly than does the lithium atom. As a result, the electron pair in the lithium fluoride bond is more strongly attracted to the fluorine atom than to the lithium. The energy is lower if the electrons spill toward the fluorine atom. 

The lithium fluoride bond is highly ionic in character because of the large difference in ionization energies of lithium and fluorine. Consequently, gaseous lithium fluoride has an unusually high electric dipole. 

The examples just mentioned include two elements, fluorine and lithium. Fluorine forms a weakly bound molecular solid. Lithium forms a metallic solid. Let us see how we can account for this extreme difference, applying the principles of bonding treated in Chapter 16. 

From the lithium chemistry point of view, the carbon-fluorine bond cannot be considered as a carbon-halogen bond because alkyl or aryl fluorides are not adequate starting materials in lithiation processes, due to the fact that this bond is the strongest that carbon can form . On the other hand, a possible reductive defluorination process could be important from an environmental point of view due to the difficult degradation of fluoro derivatives in nature . 

Terminal vinylic fluorine bonds in substituted allylic alkenols are reduced selectively with lithium aluminum hydride in high yields. The reduction of l,l,2-trifluoroalk-l-en-3-ols in refluxing diethyl ether affords l,2-difluoroalk-l-en-3-olsas a mixture of ( )- and (Z)-isomers in 76-82% yield together with a small amount of l,l,2-trifluoroalk-2-enes (E- and Z-isomers).82 Similarly, lithium 3,3-difluoroalk-2-ene oxides 1 afford unstable l-fluoroalk-l-en-3-ols 2 (EjZ 95 5) in 80-90% crude yields.88 84... 

List the following bonds in order of increasing ionic character the lithium-to-fluorine bond in LiF, the potassium-to-oxygen bond in K2O, the nitrogen-to-nitrogen bond in N2, the sulfur-to-oxygen bond in SO2, the chlorine-to-fluorine bond in CIF3. 

We have already treated the bonding in an F2 molecule. Since neither fluorine atom can pull an electron entirely away from the other, they compromise by sharing a pair of electrons equally. How does the chemical bonding in the lithium fluoride molecule compare ... 

Thus we can expect a stable molecular species, LiF. The term stable again means that energy is required to disrupt the molecule. The chemical bond lowers the energy because the bonding electron pair feels simultaneously both the lithium nucleus and the fluorine nucleus. That is not to say, however, that the electrons are shared equally. After all, the lithium and fluorine atoms attract the electrons differently. This is shown by the ionization energies of these two atoms ... 

The combination of two lithium atoms to give the molecule Li2 is described as involving the formation of a covalent bond.between the atoms. In a crystal of fluorine, F2, the repulsion of the unshared outer electron pairs keeps the molecules spaced so that the minimum intermolecular... 

C08-0076. Calculate the overall energy change for the formation of lithium fluoride from lithium metal and fluorine gas. hi addition to data found in Appendix C and Table 8-4. the following information is needed The bond energy of F2 is 155 kJ/mol, and lithium s enthalpy of vaporization is 159.3 kJ/mol. 

After a fluorine/chlorine exchange, a lithiated aminochlorosilane is obtained. Lithium is bound to nitrogen, the strongest Lewis base in this compound. The SiN bond is enlarged (164.2 pm) and the SiNC angle of 138.7° shows the character of the amine.17,18... 

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