Phosphine-borane
In chemistry, phosphine-boranes are organophosphorus compounds with the formula R3−nHnPBH3. They are Lewis acid-Lewis base adducts derived from organophosphines (PR3−nHn) and borane (BH3). They are generally colorless or white solids. Since these adducts are air-stable, they represent a protected form of the parent organophosphine.{{cite book |doi=10.1007/128_2014_565|chapter=Recent Advances in Synthesis of P-BH3 Compounds|title=Phosphorus Chemistry II|series=Topics in Current Chemistry|year=2014|last1=Alayrac|first1=Carole|last2=Lakhdar|first2=Sami|last3=Abdellah|first3=Ibrahim|last4=Gaumont|first4=Annie-Claude|volume=361|pages=1–82|pmid=25504072|isbn=978-3-319-15511-1}}{{cite journal |doi=10.1016/S0010-8545(98)00072-1|title=Phosphane–Boranes: Synthesis, Characterization and Synthetic Applications|year=1998|last1=Brunel|first1=Jean Michel|last2=Faure|first2=Bruno|last3=Maffei|first3=Michel|journal=Coordination Chemistry Reviews|volume=178-180|pages=665–698}}
Formation and decomplexation
Typically phosphine-boranes are produced by treating the parent phosphine with a source of borane:
:PR3−nHn + BH3 → R3−nHnPBH3
Because borane solutions are expensive or dangerous, the borane is often generated in situ, e.g., by oxidation of borohydride with iodine.{{cite book |doi=10.1002/9780470132463.ch29|chapter=Methyldiphenylphosphine-Borane and Dimethylphenylphosphine-Borane| series =Inorganic Syntheses|year=2007|last1=Mathur|first1=M. A.|last2=Myers|first2=W. H.|last3=Sisler|first3=H. H.|last4=Ryschkewitsch|first4=G. E.|title=Inorganic Syntheses |pages=128–133|volume=15|isbn=9780470132463 }}
Deprotection to liberate the phosphine is often achieved by treatment with a tertiary amine:
:R3−nHnPBH3 + R'3N → R'3NBH3 + R3−nHnP
See also
- Frustrated Lewis pair, where the borane is often tris(pentafluorophenyl)borane
- Ammonia borane, related to phosphine-borane but with ammonia or amines in place of organophosphines