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| Names | |||
|---|---|---|---|
| Other names | |||
| Identifiers | |||
3D model (JSmol) | |||
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| Properties | |||
| Cs2PuCl6 | |||
| Molar mass | 723 g·mol−1 | ||
| Density | 4.10 g/cm3 | ||
| Solubility | Soluble in dilute acids[2] | ||
| Related compounds | |||
Otheranions | Caesium hexachloroplatinate | ||
Othercations | Tetramethylammonium hexachloroplutonate(IV) | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Dicaesium hexachloroplutonate (orDCHP)[1] is a compound ofcaesium,plutonium, andchlorine with formulaCs2PuCl6. It has been used in the synthesis of otherplutonium compounds,[3]: 1184, 1190–1191 and in the purification of plutonium metal.[1]
Dicaesium hexachloroplutonate forms pale yellow crystals[3]: 1109 which adopt theK2GeF6-type structure and aretrigonal. Each plutonium atom is bonded to six chlorine atoms as discretehexachloroplutonate anions (PuCl2−6), and each caesium atom is bonded to twelve chlorine atoms. The hexachloroplutonate ion hasoctahedral molecular geometry, and in DCHP, the Pu-Clbond length is 2.62 Å. The Cs-Cl bonds have a length of 3.71 Å.[3]: 1190 [4]
DCHP is astoichiometric compound, and unlike other plutonium compounds, such asplutonium(IV) nitrate, DCHP is non-hygroscopic.[2]
DCHP is prepared by first suspending a plutonium sample in water. Then, concentratedhydrochloric acid is added to the mixture. To ensure that all the plutonium is in the +4oxidation state, anaqueous solution containingsodium chlorite is mixed in with the plutonium solution. Immediately upon addingcaesium chloride solution,Cs2PuCl6 isprecipitated, and is left to sit for 12 hours. TheCs2PuCl6 powder is then isolated byvacuum filtration, washed with concentrated HCl, and then left to dry for 8 hours at 120 °C in an oven.[5]
Because of several of its properties, such as its non-hygroscopicity, highequivalent weight, and an absence ofnon-stoichiometry, it has been proposed for use as a plutoniumprimary standard. It has been used as a reference for plutonium in its +4oxidation state.[2][5]
Before it shut down, DCHP was used atRocky Flats Plant in the separation ofamericium from plutonium metal. It was used as anoxidant to oxidize plutonium metal toplutonium(III) chloride in a moltencalcium chloridematrix. Any americium would then react with plutonium(III) chloride and be extracted into the calcium chloride matrix.[1]
Dicaesium hexachloroplutonate can undergo several reactions, and as such, it is used to prepare other plutonium compounds. For example, upon reaction withcyclopentadienylthallium inacetonitrile solution, it forms thecoordination complex(η5-C5H5)3PuCl:
It also reacts withmagnesium cyclopentadienide intetrahydrofuran to give an emerald green product, most likely(η5-C5H5)3Pu(THF) (THF=tetrahydrofuran), which loses its tetrahydrofuranligand uponsublimation to form(η5-C5H5)3Pu.Plutonium(III) chloride,PuCl3, also reacts with magnesium cyclopentadienide, though the reaction occurs much more slowly, likely becausePuCl3 has apolymeric structure whileCs2PuCl6 contains discretePuCl2−6 groups.[3]: 1190–1191
Dicaesium hexachloroplutonate can also be used to synthesizeplutonium tetrachlorideadducts. Upon reaction withamides orphosphine oxides, it forms the adductsPuCl4L2 orPuCl4L3 (L=amide or phosphine oxide).[3]: 1184
Dicaesium hexachloroplutonate reacts withammonia to form thecomplex PuCl4·~7–8NH3. It is anammine complex, meaning the ammonia groups are bonded to the plutonium atom. The complex decomposes over time to give the solid PuCl4·~5NH3, which is stable at room temperature.[6]
