Trimetaphosphate (${\mathrm{P}}_3{\mathrm{O}}_9^{3-}$)

The cyclic anion ${\mathrm{P}}_3{\mathrm{O}}_9^{3-}$ comprising three tetrahedral $\mathrm{P}{\mathrm{O}}_4$ groups linked by three P–O–P bridges. Each phosphorus has two terminal oxygen atoms. It can bind a metal through one terminal oxygen from each phosphorus.