Phosphazanes Azaphosphanes

In parallel with carbophosphanes (6.1), azaphosphanes might be classified as 

Most known phosphazanes are of the X.V or type. These include monophosphazanes such as phosphoramidates (7.2a,b), phosphoramidites (7.2c,d), diphosphazanes (7.2e) and polyphospha-zanes such as metaphosphimates (7.2g) and phosphetidines (cyclodiphosphazanes) (7.2f). 

Among the parent hydrides, phosphorus triamide (triaminophosphine) (7.3a) and the tetra aminophosphonium cation (7.3b), are known. The parent penta and hexa-amides (7.3c) and (7.3d) remain hypothetical compounds although derivatives with up to five and six P-N linkages are known, for example, (7.4). 

Most tetrahedral oxy-derivatives are conveniently derived from phosphoric, phosphorus (phosphonic) or hypophosphorous (phosphinic) acids by replacing OH with NH2. 

Similar pyramidal amino derivatives of phosphorous, phosphonous and phosphinous acids can be derived, which may, in principle at least, exist in equilibrium with tetrahedral forms. 

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