Phosphates with Cyclic Anions. The Metaphosphates

Condensed Phosphates with Cyclic Anions. The Metaphosphates 

The group name Metaphosphate includes all compounds whose ions have the composition (P03) n. On the hypothesis, which, hitherto, has not been disproved by any experiments, that pentavalent phosphorus in its oxygen compounds always has a coordination number of 4 with respect 

In fact, however, the chain ends are always terminated by OH groups (254), so that the composition of the anions is (II2Px0.1x+i)x and not 

The fact that the old literature refers to compounds with the same name which we now know to be different, and also to identical substances by different names, is due to lack of knowledge of structures, inadequate experimental methods and, above all, to the difficulty of identifying different condensed phosphates. These factors are responsible for reports of the existence of what were thought to be mono- and di-metaphosphates, which are fully discussed in Karbe and Jander s comprehensive review (158) but which have proved later to be incorrect (19, 81, 83, 117, 209, 317). A monometaphosphate would have the structure, 

From the Raman spectrum in aqueous solution the anion ring was considered to be planar (139, 268). On the other hand the infrared absorption spectrum (57) of crystals of the stable form was interpreted in favor of the more probable chair form (36). The only X-ray study of the crystalline hexahydratc (40) published up to the present has proved to be incorrect (212). 

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III, Condensed Phosphates with Cyclic Anions. The Metaphosphates. .. 14... 

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