Single- and double-cubane clusters in the multiple oxidation states [VFe(3)S(4)](3+,2+,1+)

Area of Science:

• Inorganic Chemistry
• Bioinorganic Chemistry
• Materials Science

Background:

• Vanadium-containing nitrogenase enzymes are crucial for biological nitrogen fixation.
• Understanding the structure and electronic properties of model complexes is key to elucidating enzyme mechanisms.
• Cubane-type clusters serve as important structural motifs in metalloenzymes.

Purpose of the Study:

• To synthesize novel cubane-type vanadium-iron-sulfur clusters.
• To investigate their structural, electronic, and magnetic properties.
• To explore their potential as precursors for biomimetic studies of nitrogenase.

Main Methods:

• Chemical synthesis of vanadium-iron-sulfur clusters.
• X-ray crystallography for structural determination.
• Mössbauer, magnetic susceptibility, and EPR spectroscopy for electronic and magnetic characterization.

Main Results:

• Synthesis and structural characterization of new cubane-type clusters, including a double-cubane structure.
• Spectroscopic data indicate electron delocalization and mixed-valence iron atoms.
• Demonstration of an S = 3/2 ground state for specific clusters and a diamagnetic ground state for an oxidized cluster.

Conclusions:

• The synthesized clusters are viable precursors for nitrogenase-related studies.
• Electron density changes upon oxidation are localized on the iron-sulfur subcluster.
• The findings provide valuable insights into the electronic structure of mixed-valence iron in cubane clusters.