Is SF2 a polar or nonpolar substance?

Sulfur difluoride (SF2) is a chemical compound with the formula SF2. It’s an inorganic molecule with a 98-degree bond angle between its three atoms, F-S-F. It consists of two fluorine atoms joined to one sulphur atom.

The compound’s polarity, on the other hand, is the main source of confusion among students. The sharing of charges on the molecule determines whether the compound is polar or nonpolar, and this charge is spread due to the sharing of electrons in the valence shell of an atom.

Is SF2 polar or nonpolar, then? Because the sulfur(2.58) and fluorine(3.98) atoms in the molecule have different electronegativity and the molecule has a bent geometrical structure, SF2 is polar in nature. As a result, the S-F bond’s dipoles do not cancel each other out, and molecules become polar and contribute some dipole moment.

The non-symmetrical sharing of the valence electron causes the molecule’s polarity, resulting in a region of uneven charges in the molecule.

The polarity of a molecule is created by regions with high positive charge density and high negative charge density, resulting in poles on the molecule.

What causes the SF2 to be polar?

On either side of the sulphur atom are two fluorine atoms, each with seven valence electrons in the atom’s outermost shell.

In the outermost shell of sulphur, there are six electrons. Sulfur forms a covalent bond with both fluorine atoms when it has one electron on each side.

Sulfur, on the other hand, is left with two lone pairs of electrons, whereas fluorines each have three. Because the lone pair contributes to the molecule’s shape, these lone pairs significantly alter the SF2 molecule’s usually presumed linear structure.

The fluorines will spread out more and the linear structure will bend as the fluorine atoms bend down, according to the Valence Shell Electron Repulsion Theory, or VSEPR theory.

The two lone pairs of electrons will remain on top of sulphur, while both fluorine atoms will move below, forming a bent V shape.

Because the fluorine atom is more electronegative than the sulphur atom, the shared bound electrons are pulled somewhat more to the side of the fluorine atom, giving it a partial negative charge.

Sulfur gets a partial positive charge, and the dipole moments of both S-F bonds add together to form a net dipole moment.

With this model, you can observe that the structure has two opposite sides with opposite polarity. As a result, the molecule is not rendered symmetrical, and it acquires polarity. SF2 is thus a polar molecule.

The SF2 hybridization

The middle sulphur in SF2 possesses SP3 hybridization. The orbitals on either side of the sulphur are 180 degrees apart, and the bond angle formed between them is 98 degrees, which is very similar to that of water.

What makes the SF2 bonding approach so intriguing?

Although SF2 is a polar molecule, it has a unique bonding angle. SF2 has a bond angle of 98 degrees, while H2O has a bond angle of 104 degrees.

The presence of the very negative halogen fluorine is the cause behind this. Both sides of the molecule have two fluorine atoms.

Negative-negative charge repulsion is caused by the presence of lone pair electrons. As a result, the molecule takes on a bent structure.

The positive hydrogen atoms in H2O, on the other hand, are more attracted to the lone pair.

Nonpolar vs. Polar Compounds

A polar compound has two poles with different polarities produced across it, whereas non-polar compounds do not have such a polarity zone.

We can also state that polar compounds are asymmetrical and include electrical poles, whereas non-polar compounds are symmetrical and lack electrical poles.

In nonpolar molecules, Van der Walls forces exist, whereas polar bonds have a hydrogen bond.

Factors that determine a molecule’s polarity

The polarity of a molecule is determined by a number of factors, including:

The electrons of an atom migrate towards a more electronegative atom when there is an electronegative difference between the atoms of the molecule.

The zones of negative and positive charge will develop more noticeably if the electronegative difference between the two atoms is considerable. As a result, the greater the polarity.

The spatial arrangement of bonds: The polarity of an atom can be affected by the spatial arrangement of bonds. The force exerted on the shared pair of electrons by the other bound and non-bonded electrons will modify it, resulting in polarity.

SF2’s molecular geometry?

Sulfur difluoride possesses twenty valence electrons (fourteen for both fluorine and sulphur atoms and three for sulphur), however after deducting the valence electron from the multiple of the octet, we have four valence electrons left, resulting in two electron lone pairs.

According to the VSEPR hypothesis, these lone players cause the sulphur difluoride molecule to have a tiny bond angle.

The geometry of SF2 is depicted in the graphic below.

SF2 Lewis structure

Sulfur difluoride has a Lewis structure similar to other halogen compounds, with 6 electrons in the valence shell.

Fluorine has a valence electron count of seven. Fluorine completes its octet by sharing two electrons with sulphur. As a result, the sole bond produced is covalent.

SF2’s structure

SF2 is a polar molecule that is made up of three atoms. The construction follows the SP3 pattern. Because sulphur is positive and fluorine is very negative, SF2 has a bend.

Formation of Sulfur Difluoride

The interaction of sulphur dichloride and potassium fluoride at low pressure produces sulphur difluoride. To make SF2, mercury fluoride can be substituted for potassium fluoride.

SF2 + 2KCl (SCl2 + 2KF) ———> SCl2 + 2KF

When heated to FSSF, the chemical might become highly unstable and disintegrate. This is the unsymmetrical isomer of S2f4 that is thought to rise as a result of the insertion of sulphur difluoride into the second molecule’s S-F link.

The reaction of oxygen difluoride and hydrogen sulphide is another mechanism of formation:

SF2 + H2O = OF2 + H2S

Other SF2 Reactions

The gas-phase reaction of COS with F2 was discovered to be the best SF2 synthesis. Chemistry is studied through the use of reagents in various processes.

The novel binary sulphur fluorides Sf3SF3 and SF3SSF are produced by condensation of SF2 with SF4 and SSF2.

When sulphur dioxide is heated, it decomposes into the unstable unsymmetrical FSSF3. Because this unstable molecule has a large number of link lengths, it is extremely unstable in reactions.

This chemical is stable as a solid due to the sulphur fluorine linkages. In the liquid state, it is also stable below -74 degrees Celsius.

The SF2 formal charge

The formal charge of any chemical is determined using the formula below:

Valence electrons – Unbonded electrons – Half of the bonded electrons = Formal Charge

We can count all of the required parameters in the SF2 structure and arrive at the answer to the query.

Fluorine has seven valence electrons, but we have two fluorines, thus we have a total of fourteen. We have 6 valence electrons on the sulphur atom, for a total of 20 valence electrons on the atom.

The compound has four bound atoms: two from sulphur and one from each fluorine. Instead of computing half of the bonded electrons, count the number of bonds in the atom and utilise that amount instead.

There are 18 electrons that are not bound.

As a result of the formula,

20 (V.E) – 18 (unbonded electrons) – 2 (formal charge) (half of bonded electrons)

0 formal charge

As a result, SF2 has a formal charge of 0.

SF2’s properties

It is an extremely unstable inorganic chemical molecule that decomposes to FSSF3.

Sulfoxylic difluoride is its IUPAC name.

The SF2 molecule has a molecular mass of 70.062 g/mol.


The compound is canonical, and it has a heavy atom count of three. SF2 is a bent V-shape molecule with a bond angle of 98 degrees and a difference of roughly 3.98-2.58 = 1.4 between fluorine and sulphur atoms. As a result, polarity is formed across both S-F bonds, and due to the molecule’s bent shape, both dipoles add up to give a net dipole moment, resulting in a polar molecule.

The chemical, however, is known to be exceedingly unstable and decomposes rapidly.

Read more: Is CBr4 a polar or nonpolar substance?

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


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