Akin to complexation, phosphines are readily alkylated.  For example, methyl bromide converts triphenylphosphine to the methyltriphenylphosphonium bromide, a "quat salt":
:PPh  +  CHBr  →  [CHPPh]Br
Phosphines are nucleophilic catalysts in organic synthesis, e.g. the Rauhut–Currier reaction and Baylis-Hillman reaction.