Plutonium(IV) sulfate
{{chembox
| Name = Plutonium(IV) sulfate
| IUPACName = Plutonium(IV) sulfate
| Section1 = {{Chembox Identifiers
| index_label=anhydrous
| index1_label=tetrahdyrate
| PubChem =
| PubChem1 =
| InChI=1S/2H2O4S.Pu/c2*1-5(2,3)4;/h2*(H2,1,2,3,4);/q;;+4/p-4
| InChIKey=QRGPRHDJXDGLIN-UHFFFAOYSA-J
| InChI1 = InChI=1S/2H2O4S.4H2O.Pu/c2*1-5(2,3)4;;;;;/h2*(H2,1,2,3,4);4*1H2;/q;;;;;;+4/p-4
| InChIKey1 = UAJVPPUGRHQMOQ-UHFFFAOYSA-J
| SMILES = O=S(=O)([O-])[O-].O=S(=O)([O-])[O-].[Pu+4]
| SMILES1 = O=S(=O)([O-])[O-].O=S(=O)([O-])[O-].[Pu+4].O.O.O.O
}}
| Section2 = {{Chembox Properties
| Formula = Pu(SO4)2
| MolarMass = 506.18 g/mol
| Solubility = Somewhat solubleNBL Program Office, "Safety Data Sheet: Plutonium Sulfate Tetrahydrate", https://www.energy.gov/sites/prod/files/2020/11/f80/SDS-Plutonium_Sulfate_2020.pdf
| MeltingPt = ~800°C? (Decomposes){{cite journal |date=1 July 1961 |title="Thermogravimetric Behavior of Plutonium Metal, Nitrate, Sulfate, and Oxalate" |author=Waterbury, Glenn R., Douglass, Robert M., Metz, Charles F. |journal=Analytical Chemistry |doi=10.1021/ac60176a047 |volume=33 |issue=8 |pages=1018–1023}}
| Appearance = Red crystalline solid{{cite journal |date= 18 May 2011 |title=Structural Periodicity in Plutonium(IV) Sulfates |author=Richard E. Wilson |journal=Inorganic Chemistry |pmid=21591736 |doi=10.1021/ic200384h |volume=50 |issue=12 |pages=5663–5670}}}}
| Section3 = {{Chembox Structure
| CrystalStruct = Orthorhombic
| SpaceGroup = Fddd (α-Pu(SO4)2·4H2O){{cite journal |date=25 Aug 2010 |title=The crystal structures of α- and β-forms of plutonium(IV) sulphate tetrahydrate |author=Jayadevan, N.C., Mudher, K.D.S., Chackraburtty, D.M. |journal=Zeitschrift für Kristallographie - Crystalline Materials |doi=10.1524/zkri.1982.161.14.7 |volume=161 |issue=1–4 |pages=7–14}}
Pnma (β-Pu(SO4)2·4H2O)
| PointGroup = mmm (α-Pu(SO4)2·4H2O)}}
| Section4 = {{Chembox Related
| OtherAnions = Plutonium(IV) oxide
Plutonium(IV) fluoride
| OtherCations = Uranium(IV) sulfate
Uranyl sulfate}}
}}
Plutonium(IV) sulfate is an inorganic salt consisting of plutonium and sulfate ions, with the chemical formula Pu(SO4)2·xH2O. It has been observed as a tetrahydrate, where x=4, as well as an anhydrous form, where x=0. The tetrahydrate has been used as a primary analytical standard for plutonium.{{cite journal |date= 1 Nov 1962 |title=The stability of plutonium sulphate tetrahydrate, an analytical standard: a ten-year evaluation |author=C. E. Pietri, A. W. Wenzel |journal=Talanta |pmid=18960954 |doi=10.1016/0039-9140(71)80138-8 |volume=18 |issue=8 |pages=849–852}}
Formation & Reactions
Plutonium(IV) sulfate is produced when plutonium(IV) ions react with bisulfate or sulfate ions in aqueous solution:Lemire, R. J. et al., Chemical Thermodynamics of Neptunium and Plutonium, Elsevier, Amsterdam, 2001.
:{{chem2|Pu(4+)(aq) + 2 HSO4-(aq) -> Pu(SO4)2(aq) + 2 H+(aq)}}
:{{chem2|Pu(4+)(aq) + 2 SO4(2-)(aq) -> Pu(SO4)2(aq)}}
At high temperatures (~800°C), plutonium(IV) sulfate tetrahydrate decomposes. It first releases its water to form anhydrous plutonium(IV) sulfate, then releases sulfur oxides to form plutonium(IV) oxide.
At normal temperatures, however, plutonium(IV) sulfate tetrahydrate is stable in air, even at high humidity.{{cite journal |date= 1 Nov 1962 |title=Plutonium Sulfate Tetrahydrate, a Proposed Primary Analytical Standard for Plutonium |author=C. E. Pietri |journal=Analytical Chemistry |doi=10.1021/ac60192a027 |volume=163 |issue=12 |pages=130–136}}
Structure
Plutonium(IV) sulfate tetrahydrate ligands are monodentate, with bonds between plutonium atoms and oxygen atoms in the water and sulfate molecules. Each plutonium atom has a coordination number of 8, and a coordination geometry of square antiprismatic. Plutonium(IV) sulfate tetrahydrate crystals have an orthorhombic crystal structure. Hydrogen bonds exist between hydrogen atoms in the water molecules and oxygen atoms in the sulfate ions that are not attached to the plutonium atom.
= Allotropes =
Plutonium(IV) sulfate tetrahydrate has two allotropes– α-Pu(SO4)2·4H2O and β-Pu(SO4)2·4H2O. The two forms share the same molecular geometry, but differ in the functional nature of the hydrogen bonds. The α-form transitions into the β-form at ~120°C.
α-Pu(SO4)2·4H2O has a unit cell with dimensions a=26.53Å, b=12.00Å, and c=5.69Å, where there are 8 formula units per unit cell.
β-Pu(SO4)2·4H2O has a unit cell with dimensions a=14.54Å, b=10.98Å, and c=5.67Å, where there are 4 formula units per unit cell.
Hazards
Plutonium(IV) sulfate is a highly dangerous compound, due to it being radioactive and carcinogenic.