Tetramethylphosphonium bromide explained

Tetramethylphosphonium bromide is an organophosphorus compound with the formula (CH3)4PBr. It is a white, water-soluble solid, the salt of the cation tetramethylphosphonium and the bromide anion. It is prepared by treating trimethylphosphine with methyl bromide.

Reactions

Deprotonation gives methylenetrimethylphosphine ylide, which can sustain a second deprotonation:[1]

(CH3)4PBr + BuLi → CH3)3P=CH2 + LiBr + BuH

CH3)3P=CH2 + BuLi → CH3)2P(CH2)2Li + BuHThe latter is a precursor to many coordination complexes, e.g., the dicuprous complex Cu2[(Me<sub>2</sub>P(CH<sub>2</sub>)<sub>2</sub>]2.[2]

References

  1. Book: Trimethylphosphonium Methylide (Trimethyl Methylenephosphorane). H. F. Klein. Inorganic Syntheses . 1978. XVIII. 138–140. 10.1002/9780470132494.ch23. 978-0-471-03393-6 .
  2. Schmidbaur, H.. Phosphorus Ylides in the Coordination Sphere of Transition Metals: An Inventory. Angewandte Chemie International Edition in English. 1983. 22. 12. 907–927. 10.1002/anie.198309071.