Aminophosphine

In organophosphorus chemistry, an aminophosphine is a compound with the formula R_2−nP(NR₂)n where R = H or an organic substituent, and n = 0, 1, 2. At one extreme, the parent H₂PNH₂ is lightly studied and fragile, but at the other extreme tris(dimethylamino)phosphine (P(NMe₂)₃) is commonly available. Intermediate members are known, such as Ph₂PN(H)Ph. These compounds are typically colorless and reactive toward oxygen. They have pyramidal geometry at phosphorus.^[1]

Synthesis and reactions

Typical aminophosphines undergo many of the reactions of tertiary phosphines: (i) oxidation to the oxide, (ii) P-alkylation (e.g. by methyl iodide) to the phosphonium cation, and (iii) coordination to soft metal electrophiles.

Aminophosphines are characteristically prepared by treatment of a chlorophosphine with a primary or secondary amine. Illustrative is the reaction of chlorodiphenylphosphine and diethylamine:^[1]

Ph₂PCl + 2 HNEt₂ → Ph₂PNEt₂ + [H₂NEt₂]Cl

The P-N bond is susceptible to alcoholysis:

Ph₂PNEt₂ + ROH → Ph₂POR + HNEt₂

The P-N bond reverts to the chloride upon treatment with anhydrous hydrogen chloride:

Ph₂PNEt₂ + 2 HCl → Ph₂PCl + [H₂NEt₂]Cl

References

1 2 Mateo Alajarín; Carmen López-Leonardo; Pilar Llamas-Lorente (2005). "The Chemistry of Phosphinous Amides (Aminophosphanes): Old Reagents with New Applications". Top. Curr. Chem. 250: 77–106. doi:10.1007/b100982.

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[Alaj-1] 1 2 Mateo Alajarín; Carmen López-Leonardo; Pilar Llamas-Lorente (2005). "The Chemistry of Phosphinous Amides (Aminophosphanes): Old Reagents with New Applications". Top. Curr. Chem. 250: 77–106. doi:10.1007/b100982.