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The Bromine pentachloride Lewis structure is Br–Cl single bond, Br–Cl single bond, Br–Cl single bond, Br–Cl single bond and Br–Cl single bond; the central Br has 6 electron domains (1 lone pair), giving a octahedral electron-domain arrangement and a square pyramidal molecular geometry with a 90° bond angle. Br is best described as sp3d2-hybridized, and Bromine pentachloride is polar because the square pyramidal shape (and/or unequal terminal atoms) prevents cancellation of the bond dipoles.
Figure 1: Lewis Structure of Bromine pentachloride (BrCl5)
| Chemical Formula | BrCl5 |
| CAS Number | 21198-04-9 |
| Total Valence Electrons | 42 |
| Lewis Structure | Br–Cl single bond, Br–Cl single bond, Br–Cl single bond, Br–Cl single bond and Br–Cl single bond |
| Electron-Domain Geometry | octahedral |
| Molecular Geometry | square pyramidal |
| Hybridization Model | sp3d2 (central Br) |
| Bond Angle | 90° |
| Polarity | Polar molecule |
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.
To draw the Bromine pentachloride Lewis structure we first count the total valence electrons. BrCl5 contains 7 (Br) + 5×7 (Cl); the net charge of 0 gives a total of 42 valence electrons to place.
The central atom is Br. 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).
Total valence electrons = 7 (Br) + 5×7 (Cl) = 42 electrons.
Place Br 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: Br–Cl single bond, Br–Cl single bond, Br–Cl single bond, Br–Cl single bond and Br–Cl single bond; one lone pair on Br.
Counting bonding and nonbonding electrons around Br therefore satisfies the octet/expanded-octet requirement for the drawn structure.
VSEPR theory states that the 6 electron domains around Br arrange to minimize mutual repulsion, giving an octahedral electron-domain geometry.
Because 1 of these domains are lone pair(s) — and lone pairs repel more strongly than bonding pairs — the observed molecular geometry is square pyramidal; the Br bond angle is set to 90° rather than the ideal value for the electron-domain geometry.
A useful VSEPR approximation is: lone pair–lone pair repulsion > lone pair–bonding pair repulsion > bonding pair–bonding pair repulsion. With 1 lone pair(s) on Br, the lone-pair domains occupy positions that minimize overall repulsion while pushing the bonding domains (and therefore the bonded atoms) closer together.
In the conventional localized-bond model, Br uses sp3d2 hybrid orbitals to form the 6 equivalent electron-domain directions (5 bonding + 1 lone pair).
Formal charge on central Br = V − N − ½B = 7 − 2 − ½×10 = 0. The preferred Lewis structure carries zero formal charge on the central atom (and on the terminals), so it is the dominant contributor.
Bromine pentachloride is polar. The square pyramidal 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.
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 Bromine pentachloride the square pyramidal 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.
| Species | Formula | Central Atom | Electron Domains | Molecular Geometry | Polarity |
|---|---|---|---|---|---|
| Bromine pentachloride | BrCl5 | Br | 6 | square pyramidal | Polar |
| Bromine trifluoride | BrF3 | Br | 5 | T-shaped | Polar |
| Hydrogen bromide | HBr | Br | 4 | linear (diatomic) | Polar |
Bromine pentachloride is polar. Its square pyramidal geometry (and/or unequal terminal atoms) stops the bond dipoles from cancelling.
Br–Cl single bond, Br–Cl single bond, Br–Cl single bond, Br–Cl single bond and Br–Cl single bond; one lone pair on Br. It uses all 42 valence electrons and the preferred structure carries zero formal charge on the central atom.
The Br angle is about 90°. Lone-pair repulsion compresses the angle from the ideal octahedral value.
The conventional model is sp3d2. Bromine pentachloride has 6 electron domains around the central Br.
The CAS number is 21198-04-9. PubChem and NIST identify this with BrCl5; use it to locate suppliers and database records.
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 21198-04-9 identifies the substance, not a universal purity specification.
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