Praseodymium in the formal +5 oxidation state.

Area of Science:

• Inorganic Chemistry
• Lanthanide Chemistry
• Organometallic Chemistry

Background:

• Praseodymium in the +5 oxidation state is rare and connects diverse metal redox chemistries.
• Previous evidence for molecular pentavalent praseodymium was limited to gas-phase and matrix isolation studies.

Purpose of the Study:

• To synthesize and characterize a stable molecular complex of praseodymium in the +5 oxidation state.
• To investigate the electronic structure and bonding in high-valent praseodymium complexes.

Main Methods:

• Low-temperature synthesis of the praseodymium complex [Pr(NPtBu3)4][X].
• Characterization using single-crystal X-ray diffraction and solution-state spectroscopy.
• Computational analysis including density functional theory and multireference wavefunction methods.

Main Results:

• Successful synthesis and characterization of a molecular pentavalent praseodymium complex.
• Identification of a highly multiconfigurational singlet ground state.
• Determination that an inverted ligand field dictates the unique electronic structure.

Conclusions:

• The synthesized complex represents a significant advancement in understanding high-valent metal bonding.
• This work establishes a critical link between lanthanide, early-transition, and actinide redox chemistries.
• The findings offer new insights into the behavior of praseodymium in unusual oxidation states.