Plutonium (Pu) is an actinide metal. It is used for nuclear fuel and as an agent for fission in nuclear weapons. This element has some unique properties, which are based on its unusual 5f electronic structure. The electronic structure of plutonium provides insight into how it interacts with the surrounding environment.
Plutonium consists of six allotropes at ambient pressure. Each of the allotropes is characterized by a different oxidation state. For example, the +4 oxidation state is stable in the system, whereas the +6 oxidation state is highly unstable.
Pu(V) has lower effective charge than the other valence states. However, it is still present in the system as a hydrated ion. In acidic solutions, it is a stable ion with a bright green color.
Plutonium can be separated into binary compounds with oxygen and halogens. Most complexes are Pu(IV) or Pu(VI). Branched alkyl chain amides have been prepared as partially outer-sphere complexes. These amides have protonated ligands hydrogen bonded to nitrate ions.
Plutonium has a low melting temperature. It is also the element with the highest electrical resistivity of all metallic elements. To understand its electronic structure, the researchers used the density functional theory (DFT) method. Structural parameters and Debye-Waller factors were computed from DFT calculations. Their X-ray diffraction pattern was not indexed from the molten state.
Researchers at the Argonne National Laboratory and the University of Notre Dame have studied the structure of plutonium nanoclusters. They found that steric repulsions and cavity effects helped stabilize the Pu(V) in the 18-crown-6 ligand complex.