Arsenic-Rich Polyarsenides Stabilized by Cp*Fe Fragments

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Investigation into the redox behavior of [Cp*Fe(η⁵-As₅)] (1), a complex analogous to its phosphorus counterpart.
• Exploration of the reactivity of arsenic clusters stabilized by transition metal fragments.

Purpose of the Study:

• To investigate the redox chemistry of [Cp*Fe(η⁵-As₅)] (1).
• To synthesize and characterize novel arsenic-metal scaffolds formed via chemical reduction.
• To determine the structural diversity and stability of resulting polyarsenide complexes.

Main Methods:

• Cyclic voltammetry to study redox behavior.
• Chemical reduction using KH to induce cluster formation.
• Single-crystal X-ray diffraction, NMR, EPR, and mass spectrometry for characterization.
• Density Functional Theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• Redox behavior of [Cp*Fe(η⁵-As₅)] (1) is similar to its phosphorus analog.
• Chemical reduction yields novel arsenic-rich scaffolds (As₁₀, As₁₄, As₁₈) stabilized by [Cp*Fe] fragments.
• Discovery of the largest anionic Asₙ ligand complexes reported to date, including a triple-decker complex.
• DFT calculations suggest rapid dimerization of the initial reduced species to form a dianionic As₁₀ complex.

Conclusions:

• The [Cp*Fe] fragment effectively stabilizes a wide range of arsenic cluster sizes and architectures.
• This work significantly expands the known family of polyarsenide complexes and their structural diversity.
• The findings provide insights into the formation and stabilization mechanisms of complex arsenic frameworks.