Selenium hexachloride Lewis Structure

Selenium hexachloride Lewis Structure: Cl₆Se Lewis Structure, octahedral Geometry, sp3d2 Hybridization & Polarity

Selenium hexachloride Key Facts

The Selenium hexachloride Lewis structure is Se–Cl single bond, Se–Cl single bond, Se–Cl single bond, Se–Cl single bond, Se–Cl single bond and Se–Cl single bond; the central Se has 6 electron domains (0 lone pairs), giving a octahedral electron-domain arrangement and a octahedral molecular geometry with a 90° bond angle. Se is best described as sp3d2-hybridized, and Selenium hexachloride is nonpolar because the bond dipoles cancel by molecular symmetry.

Figure 1: Lewis Structure of Selenium hexachloride (Cl₆Se)

Chemical Formula	Cl₆Se
CAS Number	117596-63-9
Total Valence Electrons	48
Lewis Structure	Se–Cl single bond, Se–Cl single bond, Se–Cl single bond, Se–Cl single bond, Se–Cl single bond and Se–Cl single bond
Electron-Domain Geometry	octahedral
Molecular Geometry	octahedral
Hybridization Model	sp3d2 (central Se)
Bond Angle	90°
Polarity	Nonpolar molecule

PubChem and NIST list Selenium hexachloride as Cl ₆Se with CAS 117596-63-9; molecular weight ≈ None g/mol. View CAS 117596-63-9 dictionary details on Guidechem →

Applications of Selenium hexachloride (CAS 117596-63-9)

This organic compound is used as a solvent, intermediate or specialty reagent in fine-chemical, pharmaceutical and materials synthesis; specify grade and impurity profile when sourcing.

Solvent / Reagent Medium for reactions, extraction or formulation.

Intermediate Building block for downstream derivatives.

Specialty Use Targeted role in pharma/fragrance/materials.

Procurement Note "Selenium hexachloride" is supplied in multiple commercial grades and package sizes. Specify purity, grade, moisture/impurity limits, package (cylinder, drum or bulk) and intended process, and use CAS 117596-63-9 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Selenium hexachloride Lewis structure we first count the total valence electrons. Cl₆Se contains 6×7 (Cl) + 6 (Se); the net charge of 0 gives a total of 48 valence electrons to place.

The central atom is Se. It is the least electronegative atom capable of forming multiple bonds and is surrounded by the more electronegative terminal atom(s); hydrogen, when present, always occupies a terminal position. Electronegativity considerations place the electron density toward the terminal atom(s).

Valence-electron count

Total valence electrons = 6×7 (Cl) + 6 (Se) = 48 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place Se at the center and connect each surrounding atom with a single bond, complete octets on the terminal atoms, and place any remaining electrons on the central atom. The resulting electron distribution is: Se–Cl single bond, Se–Cl single bond, Se–Cl single bond, Se–Cl single bond, Se–Cl single bond and Se–Cl single bond; no lone pairs on Se.

Counting bonding and nonbonding electrons around Se therefore satisfies the octet/expanded-octet requirement for the drawn structure.

Se–Cl Se–Cl Se–Cl Se–Cl Se–Cl Se–Cl

Se: 0 lone pairs, 6 bonding domains

6 bonding domains + 0 lone pairs = 6 electron domains

Expanded Octet: d-Orbital Participation Central Se belongs to period 3 or below, so it can accommodate more than eight electrons: low-lying d orbitals become available and the octahedral arrangement with 6 domains reflects this expanded valence shell. The octet rule alone does not apply to such hypervalent species.

Step 3 - VSEPR Theory & Geometry

VSEPR theory states that the 6 electron domains around Se arrange to minimize mutual repulsion, giving an octahedral electron-domain geometry.

Because 0 of these domains are lone pair(s) — and lone pairs repel more strongly than bonding pairs — the observed molecular geometry is octahedral; the Se bond angle is set to 90° rather than the ideal value for the electron-domain geometry.

Repulsion hierarchy

A useful VSEPR approximation is: lone pair–lone pair repulsion > lone pair–bonding pair repulsion > bonding pair–bonding pair repulsion. With 0 lone pair(s) on Se, the lone-pair domains occupy positions that minimize overall repulsion while pushing the bonding domains (and therefore the bonded atoms) closer together.

Hybridization & Formal Charge

In the conventional localized-bond model, Se uses sp3d2 hybrid orbitals to form the 6 equivalent electron-domain directions (6 bonding + 0 lone pair).

Formal-charge check

Formal charge on central Se = V − N − ½B = 6 − 0 − ½×12 = 0. The preferred Lewis structure carries zero formal charge on the central atom (and on the terminals), so it is the dominant contributor.

Modeling Note Modeling Note: sp3d2 / sp3d2 hybridization is a convenient localized-bond teaching model. Modern quantum-chemical descriptions of hypervalent Selenium hexachloride use molecular orbitals and do not require populated d orbitals as the primary bonding picture.

Is Selenium hexachloride Polar or Nonpolar?

Selenium hexachloride is nonpolar. Although individual Se–terminal bonds are polar when the atoms differ in electronegativity, the octahedral geometry makes their vector sum zero, so there is no net molecular dipole.

Expert Quote — Structural Chemistry Perspective

A common misconception is that polar bonds guarantee a polar molecule. Selenium hexachloride shows the opposite: identical bond dipoles arranged with octahedral symmetry cancel exactly, yielding a nonpolar species.

Interpretation consistent with standard VSEPR / molecular-geometry references.

Its nonpolar character governs solvation and intermolecular behavior; specify grade and handling when sourcing.

Structural Comparison Table

Species	Formula	Central Atom	Electron Domains	Molecular Geometry	Polarity
Selenium hexachloride	Cl₆Se	Se	6	octahedral	Nonpolar
Selenium dioxide	O₂Se	Se	3	bent	Polar
Hydrogen selenide	H₂Se	Se	4	bent	Polar

Practice question Starting from the 48 valence electrons of Cl₆Se, draw the Lewis structure and confirm the central Se atom is sp3d2-hybridized with octahedral geometry. What happens to the bond angle if one terminal atom is replaced by a more electronegative substituent?

Looking for industrial bulk or specified-grade supplies of Selenium hexachloride (CAS 117596-63-9)? Browse Supplier on Guidechem →

FAQs

Is Cl₆Se polar or nonpolar?

Selenium hexachloride is nonpolar. Its octahedral symmetry cancels the bond dipoles exactly.

What is the Lewis structure of Selenium hexachloride?

Se–Cl single bond, Se–Cl single bond, Se–Cl single bond, Se–Cl single bond, Se–Cl single bond and Se–Cl single bond; no lone pairs on Se. It uses all 48 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Selenium hexachloride?

The Se angle is about 90°. Lone-pair repulsion compresses the angle from the ideal octahedral value.

What is the hybridization of Se in Selenium hexachloride?

The conventional model is sp3d2. Selenium hexachloride has 6 electron domains around the central Se.

What is the CAS number of Selenium hexachloride?

The CAS number is 117596-63-9. PubChem and NIST identify this with Cl₆Se; use it to locate suppliers and database records.

References

PubChem, Selenium hexachloride. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Selenium hexachloride. Formula, CAS Registry Number and thermochemical / spectroscopic data.
IUPAC Gold Book. Definitions for "lone pair", "VSEPR", "hybridization" and "formal charge".
Atkins, P. & de Paula, J., Physical Chemistry. VSEPR, molecular geometry and dipole moments.
Guidechem supplier & dictionary records. Commercial sourcing and CAS-linked property pages for Selenium hexachloride (CAS 117596-63-9).

Technical scope: Lewis structures, VSEPR and hybridization are model-based descriptions for chemical communication and structure prediction; actual molecular electronic structure is more accurately represented by molecular-orbital and quantum-chemical methods. Commercial grades vary substantially by supplier and intended use; CAS 117596-63-9 identifies the substance, not a universal purity specification.

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Selenium hexachloride Lewis Structure

Selenium hexachloride Lewis Structure