Iminophosphorane (or, more correctly, phosphanimine) is a kind of organophosphorus compound with the formula R3PNR'. Like the corresponding phosphine oxides and Wittig reagents, phosphanimines are ylides. Their bonding is described by two resonance structures.

Preparation

Aza-ylides can be obtained via the reaction of a tertiary phosphine and an organic azide with the loss of dinitrogen. Triphenylphosphine is a commonly used phosphine.

Examples

The parent phosphanimine has the formula H3P\dNH (registry number 25682-80-8) remains only of theoretical interest. Of practical value are derivatives of triorganophosphines and organic amines. A prototype is the phenyl imide derivative of triphenylphosphine, a white, lipophilic solid. Bis(triphenylphosphine)iminium chloride, a common iminophosphorane, is prepared in two steps from triphenylphosphine Ph3P: A phosphanimine is obtainable from trimethylsilyl azide and triphenylphosphine. Desilylation gives the anion Ph3P\dN-.

Reactions

Phosphanimines are one of the components in the aza-Wittig reaction. The other component is an aldehyde or a ketone. They also are components of the Staudinger ligation.