Potassium diplatinum(II) tetrakispyrophosphite

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.^[1]

Potassium diplatinum(II) tetrakispyrophosphite

Names
Other names platinum pop
Identifiers
CAS Number	80011-26-3
3D model (JSmol)	Interactive image
InChI InChI=1S/4K.4O5P2.2H2O.2Pt/c;;;;4*1-6(2)5-7(3)4;;;;/h;;;;;;;;2*1H2;;/q4*+1;;;;;;;2*-6/p+8 Key: KEWZHLOBJOYCDC-UHFFFAOYSA-V
SMILES [K+].[K+].[K+].[K+].[Pt+2]1234[Pt+2]([P-](=O)(O)O[P-](=O)(O)1)([P-](=O)(O)O[P-](=O)(O)2)([P-](=O)(O)O[P-](=O)(O)3)[P-](=O)(O)O[P-](=O)(O)4.O.O
Properties
Chemical formula	H8K4O20P8Pt2
Molar mass	1122.395 g·mol−1
Appearance	yellow solid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis and reactions

The complex is prepared by heating a mixture of potassium tetrachloroplatinate and phosphorous acid:^[2]

2 K₂PtCl₄ + 8 H₃PO₃ → K₄[Pt₂(HO₂POPO₂H)₄] + 8 HCl + 4 H₂O

Several quat salt derivatives are known.^[3][4]

The anion reacts with boron trifluoride to give the BF₂-capped complex [Pt₂(P₂PO₅)₄(BF₂)₈]^4-.^[5]

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.

Structure

The pair of square-planar platinum(II) centers are bridged by four pyrophosphito (HO(O)POP(O)OH^2-) 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.^[1]