Plutonium oxysulfides

Plutonium oxysulfides are compounds of plutonium, oxygen and sulfur, where sulfur exists as sulfide or polysulfide ions and plutonium exists in the trivalent state or tetravalent state. They are mixed oxide-sulfides and include Pu₂O₂S, Pu₄O₄S₃, PuOS, and Pu₂O₂S₃.^[1]

Compounds

Pu₂O₂S

Diplutonium dioxide monosulfide (Pu₂O₂S) is formed by reacting plutonium(III) oxide and plutonium sesquisulfide at 1400 °C:^[1]

2 Pu₂O₃ + Pu₂S₃ → 3 Pu₂O₂S

Or the decomposition of Pu₄O₄S₃ at 1100 °C.^[1]

It is isostructural with (has the same structure as) cerium(III) oxysulfide, having a hexagonal structure with lattice parameters a=3.929 and c=6.768 Å.^[1]

Pu₄O₄S₃

Tetraplutonium tetroxide trisulfide (Pu₄O₄S₃) is formed by the decomposition of PuOS at 600 °C. It is a mixed valence compound, containing a 1:1 ratio of plutonium in its +3 and +4 oxidation states. It has a complex pseudo-hexagonal structure, with lattice parameters a=4.06, b=6.72, c=3.87 Å, and β=118°.^[1]

PuOS

Plutonium monoxide monosulfide (PuOS) is formed by reacting sulfur with Pu₂O₂S at 500 °C (though this process also creates Pu₂O₂S₃), or by reacting plutonium monosulfide with oxygen:^[1]

PuS + ½ O₂ → PuOS

It is unstable, dissociating to Pu₄O₄S₃ at 600 °C. It adopts the same structure as uranium oxysulfide, UOS, with which it forms a solid solution. Its structure is tetragonal, with lattice parameters a=3.80 and c=6.59 Å. It contains plutonium in its +4 oxidation state.^[1]

Pu₂O₂S₃

Diplutonium dioxide trisulfide (Pu₂O₂S₃) is the other product formed by reacting Pu₂O₂S with sulfur. It is a polysulfide (compound containing sulfur-sulfur bonds) with plutonium in its +4 oxidation state, and its formula can be written as (Pu⁴⁺)₂(O²⁻)₂S²⁻(S2−2). It has a tetragonal structure with lattice parameters a=3.95 and c=7.95 Å.^[1]

See also

• Neptunium sulfides
• Plutonium sulfides