Phosphorane reactions, electronic effects

For a coordinated NH2 group in aqueous solution, there is no capability for competition as above that would lead to the same product, and hence the intramolecular nature of the reaction is clearly defined. The reactivity of this group is illustrated in the simple reaction with [Co(NH3)5(OPC>3R)]+ in aqueous base (Figure 6.10). Here, the nucleophile can attack at the adjacent and relatively electron-deficient P atom, leading to a new N—P bond forming. The phosphorane intermediate formed has in effect one too many bonds around the P, relieved by a P—O bond breaking to release an alkoxide ion. 

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