Phosphorus heptabromide

For the pigment code PBr7, see List of inorganic pigments § Brown pigments.

Phosphorus heptabromide is an inorganic compound with the chemical formula PBr₇. It is one of the phosphorus bromides. At normal conditions, it forms red prismatic crystals. PBr₇ can be prepared by the sublimation of a mixture of phosphorus pentabromide and bromine.^[2]

PBr₅ + Br₂ → PBr₇

Phosphorus heptabromide

Names
IUPAC name Tetrabromophosphanium tribromide
Other names Perbromophosphonium tribromide Phosphorus heptabromide Tetrabromophosphonium tribromide
Identifiers
CAS Number	14337-11-2 Y
3D model (JSmol)	Interactive image
ChemSpider	57450667
PubChem CID	71308257
CompTox Dashboard (EPA)	DTXSID60745445
InChI InChI=1S/Br4P.Br3/c1-5(2,3)4;1-3-2/q+1;-1 Key: QBFSXBUUGDHSFY-UHFFFAOYSA-N
SMILES Br[P+](Br)(Br)Br.Br[Br-]Br
Properties
Chemical formula	PBr7
Molar mass	590.302 g·mol−1
Appearance	Red prismatic crystals
Structure[1]
Crystal structure	Orthorhombic
Space group	Pnma, No. 64
Lattice constant	a = 9.35 Å, b = 7.94 Å, c = 14.69 Å
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

The structure of PBr₇ consists of a tetrabromophosphonium cation [PBr₄]⁺, paired with a tribromide anion [Br₃]⁻, and the tribromide anion is non-symmetric.^[1]

See also

• Phosphorus tribromide
• Phosphorus pentabromide