Potassium diplatinum(II) tetrakispyrophosphite (abbreviated as [Pt2(pop)4]4−) is the inorganic compound with the formula K4[Pt2(HO2POPO2H)4]. 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 μs.
Structure 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)OH2-) 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.
Synthesis and reactions The complex is prepared by heating a mixture of potassium tetrachloroplatinate and phosphorous acid: 2K2PtCl4 + 8H3PO3 → K4[Pt2(HO2POPO2H)4] + 8HCl + 4H2O Several quat salt derivatives are known.
The anion reacts with boron trifluoride to give the BF2-capped complex [Pt2(P2PO5)4(BF2)8]4-.
The compound reacts with halogens to give Pt(III) dimers: K4[Pt2(HO2POPO2H)4 + Cl2 → K4[Pt2(HO2POPO2H)4Cl2]
With substoichiometric halogen, linear chain compounds result.
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