Hexametaphosphimic acid

Pentametaphosphimic Acid and Hexametaphosphimic Acid were similarly obtained by hydrolysis in ethereal solution of the corresponding nitrilo-chlorides. Like the lower polymers they gave crystalline sodium salts containing water of crystallisation, and anhydrous penta- and hexa-silver salts by the use of ammoniacal silver nitrate. The free acids can be regenerated by the action of H2S on the silver salts. The acids are more stable towards hydrolysing agents than is trimetaphosphimic acid. 

Hexaphosphonitrilic Chloride, P6N6C112, forms long prismatic crystals. The formula was established by the methods used in the case of P6N5C1io. Hydrolysis takes place rather more readily, since hydrochloric acid is evolved when the chloride is kept in moist air. Hydrolysis in ether solution gave hexametaphosphimic acid. 

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