Thiophosphoryl bromide

Thiophosphoryl bromide is an inorganic compound with the formula PSBr₃.^[1]

Thiophosphoryl bromide

Names
Other names Thiophosphoryl tribromide Phosphorus thiobromide Phosphorothioic tribromide
Identifiers
CAS Number	3931-89-3 Y
3D model (JSmol)	Interactive image
ChemSpider	69937
ECHA InfoCard	100.021.367
EC Number	223-502-3
PubChem CID	77530
CompTox Dashboard (EPA)	DTXSID20960036
InChI InChI=1S/Br3PS/c1-4(2,3)5 Key: OWNZHTHZRZVKSQ-UHFFFAOYSA-N
SMILES S=P(Br)(Br)Br
Properties
Chemical formula	PSBr3
Molar mass	302.75 g·mol−1
Appearance	yellow crystals[1][2]
Density	2.85 g cm−3[2]
Melting point	37.8 °C (100.0 °F; 310.9 K)
Boiling point	212 °C (414 °F; 485 K) decomposes[2]
Structure[3]
Crystal structure	Cubic
Space group	Pa3, No. 205
Lattice constant	a = 11.03 Å, b = 11.03 Å, c = 11.03 Å
Molecular shape	Tetrahedral at the P atom
Related compounds
Related compounds	Phosphorus tribromide Phosphoryl bromide Thiophosphoryl fluoride Thiophosphoryl chloride Thiophosphoryl iodide Phosphorothioic chloride difluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Thiophosphoryl bromide can be prepared by heating phosphorus tribromide with phosphorus pentasulfide, or with elemental sulfur in an inert atmosphere at 130 °C.^[4]

Thiophosphoryl bromide is one product of the bromination of P₄S₇ in cold carbon disulfide:^[1]

3 P₄S₇ + 12 Br₂ → 2 PBr₃ + 2 PSBr₃ + 2 P₂S₆Br₂ + 2 P₂S₅Br₄

Structure and properties

Thiophosphoryl bromide has tetrahedral molecular geometry and C_3v molecular symmetry. According to gas electron diffraction, the phosphorus–sulfur bond length is 1.895 Å and the phosphorus–bromine bond length is 2.193 Å, while the S=P−Br bond angle is 116.2° and the Br−P−Br bond angle is 101.9°.^[5]

Thiophosphoryl bromide is soluble in carbon disulfide, chloroform and diethyl ether.^[4]

Reactions

Like other phosphoryl and thiophosphoryl halides,^[1] thiophosphoryl bromide readily hydrolyses, undergoes nucleophilic substitution and forms adducts with Lewis acids.^[6] Reaction with lithium iodide generates the mixed thiophosphoryl halides PSBr₂I and PSBrI₂ but not thiophosphoryl iodide, PSI₃.^[7] Thiophosphoryl bromide is of use in organic synthesis for reducing sulfoxides to thioethers,^[8] and sulfines to thioketones.^[9]