The Phosphorus sulfides comprise a family of inorganic compound

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

s containing only phosphorus

Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

 and sulfur

Sulfur

Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

. These compounds have the formula P₄S_x where x is less than or equal to 10. Two are of commercial significance, phosphorus pentasulfide

Phosphorus pentasulfide

Phosphorus pentasulfide is the inorganic compound with the formula P4S10. This yellow solid is the one of two phosphorus sulfides of commercial value...

 (P₂S₅), which is made on a kiloton scale for the production of other organosulfur compounds, and phosphorus sesquisulfide

Phosphorus sesquisulfide

Phosphorus sesquisulfide is the inorganic compound with the formula 43. This yellow solid is one of two commercially produced phosphorus sulfides. It is a component of "strike anywhere" matches....

 (P₄S₃), used in the production of "strike anywhere matches."

Several other phosphorus sulfides in addition to P₄S₃ and P₄S₁₀. Six of these phosphorus sulfides exist as isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

s: P₄S₄, P₄S₅, P₄S₆, P₄S₇, P₄S₈, and P₄S₉. These isomers are distinguished by Greek letter prefixes. The prefix is based on the order of the discovery of the isomers, not their structure. All known molecular phosphorus sulfides contain a tetrahedral array of four phosphorus atoms. P₄S₂ is also known but is unstable above −30 °C.

Preparation

The main method for preparing these compounds is thermolysis of mixtures of phosphorus and sulfur. The product distributions can be analyzed by ³¹P NMR spectroscopy

NMR spectroscopy

Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei to determine physical and chemical properties of atoms or the molecules in which they are contained...

. More selective syntheses entail (i) desulfurization, e.g. using triphenylphosphine

Triphenylphosphine

Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature...

 and, complementarily, (ii) sulfidation using triphenylarsine

Triphenylarsine

Triphenylarsine is the chemical compound with the formula As3. This organoarsenic compound, often abbreviated AsPh3, is a colorless crystalline solid that is used as a ligand and a reagent in coordination chemistry and organic synthesis...

sulfide.