Potassium diplatinum(II) tetrakispyrophosphite (abbreviated as [Pt<sub>2</sub>(pop)<sub>4</sub>]<sup>4âÂÂ</sup>) is the inorganic compound with the formula K<sub>4</sub>[Pt<sub>2</sub>(HO<sub>2</sub>POPO<sub>2</sub>H)<sub>4</sub>]. It is a water-soluble yellow salt. The compound has a long-lived, strongly luminescent excited state, with an emission maximum at ~510 nm and a lifetime near 10 üs.
The complex is prepared by heating a mixture of potassium tetrachloroplatinate and phosphorous acid:
Several quat salt derivatives are known.
The anion reacts with boron trifluoride to give the BF<sub>2</sub>-capped complex [Pt<sub>2</sub>(P<sub>2</sub>PO<sub>5</sub>)<sub>4</sub>(BF<sub>2</sub>)<sub>8</sub>]<sup>4-</sup>.
The compound reacts with halogens to give Pt(III) dimers:
With substoichiometric halogen, linear chain compounds result.
The anion is an example of the Chinese lantern structure. The two square-planar platinum(II) centers are bridged by four pyrophosphito (HO(O)POP(O)OH<sup>2-</sup>) ligands. The ligands interact via hydrogen bonds between the POH and P=O group. The Pt---Pt separation is 293 pm for the dihydrate. In the Pt(III) dichloride, the Pt-Pt distance is 270 pm, indicating Pt-Pt bonding.