Iodine cyanide Lewis Structure

Iodine cyanide Lewis Structure: CIN Lewis Structure, linear Geometry, sp Hybridization & Polarity

Iodine cyanide Key Facts

The Iodine cyanide Lewis structure is C–N triple bond and C–I single bond; the central C has 2 electron domains (0 lone pairs), giving a linear electron-domain arrangement and a linear molecular geometry with a 180° bond angle. C is best described as sp-hybridized, and Iodine cyanide is polar because the linear shape (and/or unequal terminal atoms) prevents cancellation of the bond dipoles.

Figure 1: Lewis Structure of Iodine cyanide (CIN)

Chemical Formula	CIN
CAS Number	506-78-5
Total Valence Electrons	16
Lewis Structure	C–N triple bond and C–I single bond
Electron-Domain Geometry	linear
Molecular Geometry	linear
Hybridization Model	sp (central C)
Bond Angle	180°
Polarity	Polar molecule

PubChem (CID 10478) and NIST list Iodine cyanide as CIN with CAS 506-78-5; molecular weight ≈ 152.922 g/mol. View CAS 506-78-5 dictionary details on Guidechem →

Applications of Iodine cyanide (CAS 506-78-5)

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 "Iodine cyanide" 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 506-78-5 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Iodine cyanide Lewis structure we first count the total valence electrons. CIN contains 4 (C) + 7 (I) + 5 (N); the net charge of 0 gives a total of 16 valence electrons to place.

The central atom is C. 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 = 4 (C) + 7 (I) + 5 (N) = 16 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place C 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: C–N triple bond and C–I single bond; no lone pairs on C.

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

C≡N C–I

C: 0 lone pairs, 2 bonding domains

2 bonding domains + 0 lone pairs = 2 electron domains

Octet Rule: Why C Has Eight Electrons C forms 2 bond(s) and retains 0 nonbonding electron(s), reaching an octet. No expanded octet is required for this second-row (or octet-satisfying) central atom.

Step 3 - VSEPR Theory & Geometry

VSEPR theory states that the 2 electron domains around C arrange to minimize mutual repulsion, giving an linear 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 linear; the C bond angle is set to 180° 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 C, 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, C uses sp hybrid orbitals to form the 2 equivalent electron-domain directions (2 bonding + 0 lone pair).

Formal-charge check

Formal charge on central C = V − N − ½B = 4 − 0 − ½×8 = 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: sp is a compact model for the 2 electron-domain directions around C; full quantum-chemical treatments use molecular orbitals.

Is Iodine cyanide Polar or Nonpolar?

Iodine cyanide is polar. The linear shape prevents cancellation of the bond dipoles. The bond dipoles do not cancel, leaving a net molecular dipole, which strongly influences solvation behavior and intermolecular interactions.

Expert Quote — Structural Chemistry Perspective

The decisive structural fact is not simply that the individual bonds are polar; it is whether molecular symmetry allows their vector sum to vanish. In Iodine cyanide the linear arrangement prevents cancellation, so a permanent dipole remains.

Interpretation consistent with standard VSEPR / molecular-geometry references.

This polarity profile underpins its behavior as a solvent, reactant or process intermediate; when sourcing, specify grade and container compatibility.

Structural Comparison Table

Species	Formula	Central Atom	Electron Domains	Molecular Geometry	Polarity
Iodine cyanide	CIN	C	2	linear	Polar
Carbon dioxide	CO₂	C	2	linear	Nonpolar
Carbon monoxide	CO	C	2	linear (diatomic)	Polar
Carbon disulfide	CS₂	C	2	linear	Nonpolar
Methane	CH₄	C	4	tetrahedral	Nonpolar
Ethane	C₂H₆	C	4	tetrahedral	Nonpolar

Practice question Starting from the 16 valence electrons of CIN, draw the Lewis structure and confirm the central C atom is sp-hybridized with linear 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 Iodine cyanide (CAS 506-78-5)? Browse Supplier on Guidechem →

FAQs

Is CIN polar or nonpolar?

Iodine cyanide is polar. Its linear geometry (and/or unequal terminal atoms) stops the bond dipoles from cancelling.

What is the Lewis structure of Iodine cyanide?

C–N triple bond and C–I single bond; no lone pairs on C. It uses all 16 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Iodine cyanide?

The C angle is about 180°. Lone-pair repulsion compresses the angle from the ideal linear value.

What is the hybridization of C in Iodine cyanide?

The conventional model is sp. Iodine cyanide has 2 electron domains around the central C.

What is the CAS number of Iodine cyanide?

The CAS number is 506-78-5. PubChem (CID 10478) and NIST identify this with CIN; use it to locate suppliers and database records.

References

PubChem CID 10478, Iodine cyanide. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Iodine cyanide. 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 Iodine cyanide (CAS 506-78-5).

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 506-78-5 identifies the substance, not a universal purity specification.

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Iodine cyanide Lewis Structure