Editing Polyphosphate (section)

== Structure==
<gallery widths="180px">
Image:Triphosphorsäure.svg|Structure of [[triphosphoric acid]]
Image:Polyphosphoric acid.svg|[[Polyphosphoric acid]]
Image:Trimetaphosphat.svg|Cyclic tri[[metaphosphate]]
Image:Adenosindiphosphat protoniert.svg|[[Adenosine diphosphate]] (ADP)
</gallery>
The structure of tripolyphosphoric acid illustrates the principles which define the structures of polyphosphates. It consists of three tetrahedral PO<sub>4</sub> units linked together by sharing oxygen centres. For the linear chains, the end phosphorus groups share one oxide and the others phosphorus centres share two oxide centres. The corresponding phosphates are related to the acids by loss of the [[acidic]] protons. In the case of the cyclic trimer each tetrahedron shares two vertices with adjacent tetrahedra.

Sharing of three corners is possible.  This motif represents [[Cross-link|crosslinking]] of the linear polymer. Crosslinked polyphosphates adopt the sheet-structure [[Silicate minerals|Phyllosilicates]], but such structures occur only under extreme conditions.