metaphosphaten.
/ˌmɛtəˈfɒsfeɪt/, U.S. /ˌmɛdəˈfɑsˌfeɪt/ Chemistry.
Originally: a salt of metaphosphoric acid; a salt containing the anion PO3−; the anion PO3−. Later: a polyanion with the general formula [(PO3)n]n−, esp. one of cyclic form with the formula (P3O9)3−.
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1833 T. Graham in Philos. Trans. (Royal Soc.) 123 277 I shall take the liberty to designate provisionally the acid of the fused biphosphate of soda, the Metaphosphoric acid..; and the fused salt itself, the Metaphosphate of soda.
1859 W. Odling in London, Edinb., & Dublin Philos. Mag. 4th Ser. 18 368 Intermediate between common or orthophosphates and metaphosphates we have several varieties of compounds, among which the best defined are the pyrophosphates, salts which result from the union of an atom of orthophosphate with an atom of metaphosphate.
1866 H. E. Roscoe Lessons Elem. Chem. xv. 136 A substance called Sodium metaphosphate, NaPO3.
1906 H. J. H. Fenton Notes Qualitative Anal. (new ed.) 30 Solution of metaphosphates (e.g. NaPO2) give with silver nitrate, white ppt. of silver metaphosphate AgPO3.
1962 F. A. Cotton & G. Wilkinson Adv. Inorg. Chem. xx. 398 These units can be incorporated into either (a) chain or polyphosphates, 2–10 P atoms, or (b) ring or metaphosphates, containing 3–7 or more P atoms.
1992 Industr. & Engin. Chem. Res. 31 360/1 The ratio (R), which is an index of the degree of polymerization of the acid,..equals 3·0 for the monomeric orthophosphate and has a limiting value of 1·0 for the very long chain metaphosphates.
This entry has been updated (OED Third Edition, December 2001; most recently modified version published online March 2022).
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