Tin triphosphide

Tin triphosphide is a binary inorganic compound of tin metal and phosphorus with the chemical formula SnP₃.^[1]

Tin triphosphide

Identifiers
CAS Number	37367-13-8 Y
3D model (JSmol)	Interactive image
SMILES [Sn+2].[Sn+4].[P-]1=[P-][P-]=[P-][P-]=[P-]1
Properties
Chemical formula	P3Sn
Molar mass	211.631 g·mol−1
Appearance	black solid
Density	4.25 g/cm3
Melting point	580 °C (1,076 °F; 853 K)
Solubility in water	insoluble
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Structure

Close up on the structure of SnP₃, highlighting the bonding around P (violet) and Sn (gray).

X-ray crystallography reveals that tin triphosphide is not a triphosphide. It is a hexaphosphide, with P₆^6- rings. These ruffled P₆ rings form three short (2.66 Å) and three long (2.95 Å) Sn-P bonds. The result is that Sn(II) adopts highly distorted octahedral geometry. The structure of tin triphosphide resembles that of gray arsenic, which also features corrugated, linked six-membered (As₆) rings, wherein each arsenic atom has a highly distorted octahedral geometry. Germanium triphosphide and tin triphosphide are similar structurally as well.

Tin triphosphide forms triclinic crystals, spatial group R3m with six formula units in a unit cell of dimensions a = 7.378 Å and c = 10.512 Å.^[2][3]

Preparation and occurrence

Tin triphosphide can be formed from the fusion of stoichiometric amounts of both elements at 580 °C:

Sn + 3P → SnP₃

SnP₃ has been evaluated for use in energy storage devices.^[4]

Related compounds

• SnP, which has the sodium chloride structure.^[5]
• Sn₄P₃^[6]