Fluorine sigma bond

Atoms with p orbitals can also form sigma bonds. Fluorine (Is 2s has a half-filled p orbital. When it reacts with another... 

Figure 7.6 The p orbitals of fluorine can combine to form a sigma bond, as illustrated here.

Fig. 9. Possible through bond coupling of fluorine lone pairs and the C-C sigma bond in cis and trans 1,2 difluoroet hylene...

Fig. 19. The sigma group MO s spanning the substituents in 1 fluoropropane as constructed from the sigma MO s of a CH bond and the fluorine sigma lone pair AO. Net stabilization results due to the Fpx-4>2 interaction...

Atoms with p orbitals can also form sigma bonds. Fluorine (Is2 2s2 2p5) has onep orbital that is half-filled. When one fluorine atom reacts with another fluorine, their two p orbitals can overlap end-to-end to form a bond that is symmetrical along the bonding... 

The remaining two p orbitals in each fluorine are oriented perpendicularly to the first p orbital. When two perpendicular p orbitals—one on each fluorine—overlap in a side-by-side configuration, they form a pi bond as shown in Figure 5.6. This bond is named after the Greek letter tt, which it resembles, at least a little. The electron clouds in pi bonds overlap less than those in sigma bonds, and they are correspondingly weaker. 

The chlorine atom in ClFj is bonded to the three fluorine atoms through sigma bonds and has two nonbonding electron lone pairs. Both lone pairs occupy equatorial positions (the largest angles in a trigonal bipyramid), resulting in a T shape for the molecule. 

The non-bonding electron on fluorine can be back-donated to the vacant orbital of another atom (boron). Boron uses three sp -hybridized orbitals to form three sigma bonds the remaining vacant pure... 

Suppose that we were interested to find out how replacement of H by F would change the MOVB wavefunction of CH2 if we were to neglect the fluorine lone pairs and consider only their sigma bonding orbitals. How can we tackle a fundamental problem of this type which time and again arises in the every-day practice of chemi stry ... 

In addition, electronegative fluorines attached to the phosphorus atom would cause a build-up in effective positive charge on the phosphorus nucleus. This, in turn, would result in a contraction of the free electron pair of the phosphorus atom. Because of the contraction in the electron pair, a sigma bond could be formed only by Lewis acids which could approach closely. In BH3 such close approach would be associated with a relatively small increase in deformation energy. On the other hand, in BF3 close approach would require such a large increase in deformation energy that... 

Inductive effects, the result of polarized sigma bonds, are important. For example, the p of 2,2,2-trifluoroethanol (CF3CH2OH) is 12.5, whereas the p of ethyl alcohol is 15.9. The fluorinated alcohol is more than a thousand times as acidic as ethyl alcohol (remember the pA scale is logarithmic). Fluorinated alcohols are always stronger acids than their hydrogen-substituted counterparts. 

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