Sodium monothiophosphate

Sodium monothiophosphate, or sodium phosphorothioate, is an inorganic compound with the molecular formula Na3PO3S(H2O)x. All are white solids. The anhydrous material (x = 0) decomposes without melting at 120-125 °C. More common is the dodecahydrate. A nonahydrate is also known.

Sodium monothiophosphate
Names
IUPAC name
Sodium monothiophosphate
Identifiers
3D model (JSmol)
ECHA InfoCard 100.030.224
EC Number
  • 233-26-1
UNII
Properties
Na3PO3S
Molar mass 180.030 g/mol
Appearance White solid
Density 1.58 g/cm3 (dodecahydrate), 2.40 g/cm3 for anhydrous
Melting point 120 to 125 °C (248 to 257 °F; 393 to 398 K) (decomposition)
soluble
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Related salts are the dithiophosphate Na3PS2O2.11H2O, trithiophosphate Na3PS3O.11H2O, and tetrathiophosphate Na3PS4.8H2O.[1]

Preparation

Sodium monothiophosphate is prepared by the base hydrolysis of thiophosphoryl chloride using aqueous sodium hydroxide:[2][3]

PSCl3 + 6 NaOH + 9 H2O → Na3PO3S.(H2O)12 + 3 NaCl

This reaction affords the dodecahydrate, which is easily dehydrated.

Partial dehydration over 6.5 M H2SO4 gives the nonahydrate. Under flowing N2, the anhydrous salt is formed.[4]

Sodium phosphorothiolate decomposes at neutral pH. Silicone grease catalyses the hydrolysis of the phosphorothioate ion, so it is recommended that it is not used in the glass joints.[5]

In the anhydrous material, the P-S bond is 211 pm and the three equivalent P-O bonds are short at 151 pm. These disparate values suggest that the P-S bond is single.[6]

References
  1. Elias, D. P. (1957). "Crystallographic Data on Some Sodium Phosphorothioates". Acta Crystallographica. 10 (9): 600. doi:10.1107/S0365110X57002108.
  2. Stanley K. Yasuda, Jack L. Lambert (1957). "Sodium Monothiophosphate". Inorganic Syntheses. Inorganic Syntheses. 5. pp. 102–104. doi:10.1002/9780470132364.ch28. ISBN 9780470132364.CS1 maint: uses authors parameter (link)
  3. L. C. Washburn, R. L. Hayes (1977). "Importance of Excess Base in the Synthesis of Sodium Monothiophosphate: (Sodium Phosphorothioate)". Inorganic Syntheses. Inorganic Syntheses. 17. pp. 193–4. doi:10.1002/9780470132487.ch53. ISBN 9780470132487.CS1 maint: uses authors parameter (link)
  4. Palazzi, Marcel (1973). "Trisodium monothiophosphate. Radiocrystallographic study". Bulletin de la Société Chimique de France. 12: 3246–8.
  5. Lucian C. Pop and M. Saito (2015). "Serendipitous Reactions Involving a Silicone Grease". Coordination Chemistry Reviews. 314: 64–70. doi:10.1016/j.ccr.2015.07.005.
  6. Pompetzki, M.; Jansen, M. (2002). "Natriummonothiophosphat(V): Kristallstruktur und Natriumionenleitfähigkeit" [Sodium monothiophosphate(V). Crystal structure and sodium ionic conductivity]. Zeitschrift fuer Anorganische und Allgemeine Chemie. 628 (3): 641–646. doi:10.1002/1521-3749(200203)628:3<641::AID-ZAAC641>3.0.CO;2-8.CS1 maint: uses authors parameter (link)


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