Unprecedented spin localisation in a metal-metal bonded dirhenium complex

Area of Science:

• Inorganic Chemistry
• Materials Science
• Solid-State Chemistry

Background:

• Edge-sharing bioctahedral complexes with short metal-metal bonds are of interest for their unique electronic properties.
• Understanding electron localization in such systems is crucial for designing novel functional materials.

Purpose of the Study:

• To elucidate the molecular and electronic structure of the edge-sharing bioctahedral complex [N(n-Bu)4]3[Re2(mnt)5].
• To investigate the factors influencing the localization of unpaired electrons in this rhenium complex.

Main Methods:

• Single-crystal X-ray diffraction to determine molecular structure.
• Computational methods to analyze electronic structure and metal-metal bond order.
• Electron Paramagnetic Resonance (EPR) spectroscopy to probe the electronic spin state.

Main Results:

• The structure of [N(n-Bu)4]3[Re2(mnt)5] was determined, revealing a short Re-Re intermetal bond length of 2.6654(2) Å.
• Computational analysis indicated a metal-metal bond order of 1.2.
• The EPR spectrum demonstrated that the unpaired electron is localized, despite the short metal-metal bond.

Conclusions:

• Asymmetric ligand distribution plays a key role in localizing the unpaired electron in [N(n-Bu)4]3[Re2(mnt)5].
• The findings provide insights into the electronic behavior of dimeric rhenium complexes with potential applications in molecular electronics or magnetism.