Phosphinoyl Phosphides

Phosphide-type anions (phosphinoyl phosphides) can be obtained by degradation of pentaphenylphosphine. 

The ethyl derivative of (6.739) reacts slowly at room temperature with trialkyl phosphines (R = Et, Bu), to produce compounds containing 2-coordinated P atoms (6.777). The latter are much more stable than the derivative R,P=PR.  

Phosphinoyl phosphides can be obtained from tris(diaIkylphosphinyl)phosphines by reaction (6.778) (R = Pr, R = Bu), and by reaction (6.779) with white phosphorus. Different proportions in the latter equation give tetra-phosphinoyl derivatives (6.780). 

In these anions, P/P/P=95° and the experimental P-P distances are a good deal less than single bond values. This suggests substantial contributions in each case, from structures of types (6.781b,c) as well as the single bonded structure (6.781a) which places two lone electron pairs on the P atom [23,24]. Alkylation removes the double bond (6.782). 

The salt from (6.778) (R — OEt, R — piperidinium) reacts with dichloroethane to give an ester based on six P atoms [25]. 

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