Is IF5 Polar or Nonpolar?

IF5Molecule

Iodine pentafluoride having its chemical formula IF5 is an interhalogen compound. It is a colorless liquid discovered by Henri Moissan in the year 1891. Many reactions undergo with the mixing of several chemical compounds with iodine pentafluoride. Many science students may have a doubt regarding whether IF5 is polar or not. I will answer this question and will discuss the surrounding topics too.

So, Is IF5 Polar or Nonpolar? IF5 is polar in nature. IF5 molecule has a bent shaped geometrical structure because of lone pair and bond pair repulsion as per VSEPR theory. Fluorine is more electronegative than iodine due to which dipole moment generates and makes the IF5 a polar molecule.

IF5 has its preferred IUPAC name as Iodine(V) fluoride. It is classified as an interhalogen compound. It is colorless liquid in appearance. Although impure IF5 is yellow in color.

It has many uses as a fluorination reagent in many chemical reactions.

Iodine pentafluoride was first prepared by burning iodine in the presence of fluorine gas. It is toxic in nature and also an oxidizer.

If we talk about the chemical composition of iodine pentafluoride, the molecule consists of five atoms of fluorine and one single atom of iodine.

The iodine contains 7 valence electrons in its outermost shell and fluorine also has 7 valence electrons present in its outermost shell.

Both atoms need one electron to get stabilized. In IF5, the five electrons get stabilize by sharing one electron of an iodine atom and iodine lacks two electrons to be shared and they are present over the iodine atom in the form of a lone pair.

It is formed by the burning of solid iodine in fluorine gas. The same method is used for producing IF5 with a better reaction environment.

I2 (solid iodine) + 5F2 (fluorine gas)    ——->    2IF5

What is Polar and Nonpolar Molecules?

Polar molecules: The two atoms forming a molecule held by a covalent bond are said to be polar if the bonded electron pair is not equally shared by both atoms. It means the charge distribution on both atoms in such molecules is not the same. Examples of such compounds are IF5, CO.

In these molecules, there exist a difference in electronegativity of atoms. More electronegative attract the bonded electron pair more towards itself and gains a partial negative charge. As a result, unequal sharing of bonded electrons takes place.

The dipole moment of these molecules also turns out to be non zero.

Nonpolar molecules: The molecules in which the atoms equally share the bonded electrons are said to be nonpolar. In such molecules, both atoms have an equal distribution of charge. Examples of such compounds are O2, CO2.

In these electrons, the geometrical shape is symmetrical and the dipole moment also turns out to be zero.

Why is IF5 a polar molecule?

One atom of iodine and five atoms of fluorine combines to form an IF5 molecule. One lone pair remains on the iodine atom and five atoms of fluorine atoms get covalently bonded with iodine atom.

As per the VSEPR theory, lone pair and bond pair repels each other. Similarly, in the case of IF5, the lone pair of electrons and bond pairs face a repulsive force that causes the bond angle set to approximately 90 degrees to each other.

Lone pair on the Iodine is at the axial position of the molecular geometry of iodine pentafluoride.

The electronegativity of fluorine is greater than that of iodine due to which the charge distribution on both atoms is unequal. It means the bonded electron pair is not equally shared by both atoms in the I-F bond.

As a result, the dipole moment value of the I-F bond comes out to nonzero. The direction of the dipole moment of all the I-F bonds is the same and therefore, the net dipole moment ads on and result in a nonzero value that determines the polarity of IF5 molecule.
There are factors that impact the polarity of a molecule. These are discussed in detail as below

Factors affecting polarity of a compound

Electronegativity: The electronegativity of an atom of a molecule is the measure of how strongly it can attract the bonded electron towards itself. Two atoms forming a covalent bond is polar if there is a difference between the electronegativity of both atoms.

Greater the difference between the electronegativity of two atoms forming a covalent bond more is the polarity.

Dipole moment: It is the measure of the polarity of a chemical compound. Greater the value of dipole moment more is the polarity of that compound. Therefore, the polarity of a chemical compound is directly proportional to its dipole moment.

Mathematically, the dipole moment is calculated as the product of the charge on the atom and the distance between atoms.

Q = charge on atom
R = bond length
D = dipole moment

D = Q*R

Molecular geometry: Molecular geometry plays an important role in checking the polarity of a molecule. It is very easy to determine the polarity of a molecule by viewing its structural geometry.

The molecule is nonpolar in nature if it has a symmetrical structure. If the shape is asymmetric, the molecule is polar.

Molecular Geometry of IF5

IF5

The IF5 has five fluorine atoms covalently bonded with iodine atom leaving behind a lone pair on iodine atom.

According to VSEPR theory, lone pair and bond pair repels each other that causes the distortion in the shape of the molecule.

Similarly, the lone pair on the iodine atom and bond pair of I_F bond causes repulsive force, and the bond angle is set such that the angle between bonds is approximately 90 degrees.

As a result, the shape of the IF5 molecule formed is square pyramidal.

Four I-F bonds lie in one plane forming a square and one I-F bond is at axis opposite to lone pair also present axial to the direction of the molecule.

Above image is the geometrical structure of the Iodine pentafluoride molecule.

Properties of IF5

  • Iodine pentafluoride is a colorless liquid at room temperature.
  • The density of this molecule is around 3.250 g/cm3.
  • The melting point of IF5 is 9.43 °C or 48.97 °F.
  • It has its boiling point of about 97.85 °C or 208.13 °F.
  • It readily reacts with water to form HF acid (hydrofluoric acid and iodic acid).
  • The viscosity of liquid iodine pentafluoride is 2.111 mPa·s.

Uses of IF5

  • Iodine fluoride is majorly used for the manufacturing of alkyl iodides containing fluorides.
  • Iodine is also used for producing the intermediate compounds for the manufacturing of polymers.
  • IF5 has its great use as a fluorinating agent in organic synthesis.

Conclusion

The IF5 molecule has a square pentagonal molecular structure due to the presence of lone pair on Iodine atom. And Fluorine is more electronegative than Iodine due to which the polarity in the I-F bond rises.

And all the I-F bonds result in a net dipole moment of complete IF5 molecule and making it a polar compound.

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