Metaphosphate

A metaphosphate ion is an oxyanion that has the empirical formula . The structure of a metaphosphate ion can be described as being made up of PO4 structural units in which each unit shares two corners with another unit. This can come about in two ways.
Metaphosphates can be considered as salts of the corresponding metaphosphoric acids (H"n"P"n"O3"n") although none of these acids has been isolated. The metaphosphoric acids can be formulated as H2O·P2O5. In comparison, phosphoric acid, H3PO4 can be formulated as 3H2O·P2O5 and pyrophosphoric acid, H4P2O7, as 2H2O·P2O5.
Metaphosphates can be used as an alternative of white phosphorus in organic syntheses.