Tris(trimethylsilyl)phosphine explained

Tris(trimethylsilyl)phosphine is the organophosphorus compound with the formula P(SiMe₃)₃ (Me = methyl). It is a colorless liquid that ignites in air and hydrolyses readily.^[1]

Synthesis

Tris(trimethylsilyl)phosphine is prepared by treating trimethylsilyl chloride, white phosphorus, and sodium-potassium alloy:^[2]

1/4 P₄ + 3 Me₃SiCl + 3 K → P(SiMe₃)₃ + 3 KClSeveral other methods exist.^[1]

Reactions

The compound hydrolyzes to give phosphine:

P(SiMe₃)₃ + 3 H₂O → PH₃ + 3 HOSiMe₃

Treatment of certain acyl chlorides with tris(trimethylsilyl)phosphine gives phosphaalkynes, one example being tert-butylphosphaacetylene.^[3]

Reaction with potassium tert-butoxide cleaves one P-Si bond, giving the phosphide salt:^[4]

P(SiMe₃)₃ + KO-t-Bu → KP(SiMe₃)₂ + Me₃SiO-t-Bu

It is a reagent in the preparation of metal phosphido clusters by reaction with metal halides or carboxylates. In such reactions the silyl halide or silyl carboxylate is liberated as illustrated in this idealized reaction:

P(SiMe₃)₃ + 3 CuCl → Cu₃P + 3 ClSiMe₃

Safety

Tris(trimethylsilyl)phosphine spontaneously ignites in air, thus it is handled using air-free techniques.

References

1. Encyclopedia: Tris(trimethylsilyl)phosphine. Kosarev, Sergey A.. Collier, Steven J.. Handbook of Reagents for Organic Synthesis. Reagents for Silicon-Mediated Organic Synthesis. 2011. 422–427. 10.1002/047084289X.rn01332 . 978-0-471-93623-7.
2. Book: Inorganic Syntheses. Becker, Gerd. Schmidt, Helmut. Uhl, Gudrun. Uhl, Werner. Tris(Trimethylsilyl)Phosphine and Lithium Bis(Trimethylsilyl)Phosphide.Bis-(Tetrahydrofuran) . 1990. 27. 243–9. 10.1002/9780470132586.ch48. 978-0-470-13258-6.
3. M. Regitz. Phosphaalkynes: new building blocks in synthetic chemistry. Chem. Rev.. 1990. 90. 191–213. 10.1021/cr00099a007. .
4. Book: Phosphaalkynes. Russell, Christopher A. . Townsend, Nell S.. Kamer, Paul C. J. . Van Leeuwen, Piet W. N. M. Phosphorus(III) Ligands in Homogeneous Catalysis. 2012. 343–354. Wiley-VCH. 10.1002/9781118299715.ch11. 978-1-118-29971-5.