page_title: Tetramethylphosphonium bromide
section_title: Reactions
hierarchical_section_title: Tetramethylphosphonium bromide / Reactions
caption_attribution_description: English: chemical structure of ((Me2P(CH2)2)Cu)2
context_page_description: 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.
context_section_description: Deprotonation gives methylenetrimethylphosphine ylide, which can sustain a second deprotonation:
  (CH₃)₄PBr  +  BuLi →  CH₃)₃P=CH₂  +  LiBr  +  BuH
  CH₃)₃P=CH₂  +  BuLi →  CH₃)₂P(CH₂)₂Li  +  BuH
  The latter is a precursor to many coordination complexes, e.g., the dicuprous complex Cu₂[(Me₂P(CH₂)₂]₂.
caption: Structure of Cu2[(Me2P(CH2)2]2.
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