Strain-Release Driven Arsenium Ion Bond Insertion.

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Synthetic Chemistry

Background:

• Insertion of pnictenium ions ([R2Pn]+) into non-polar bonds is a key area of reactivity.
• The insertion of arsenium ions ([R2As]+) presents significant synthetic challenges, often related to the high oxidation state of arsenic.
• Overcoming these challenges is crucial for developing new synthetic methodologies and understanding arsenic chemistry.

Purpose of the Study:

• To develop a novel synthetic approach for the insertion of arsenium ions into non-polar bonds.
• To circumvent the inherent limitations associated with the reactivity of [R2As]+ species.
• To synthesize and characterize new ring-expanded complexes featuring arsenium and pnictogen elements.

Main Methods:

• Development of a synthetic strategy that alleviates ring strain in the substrate.
• Utilizing transition metal complexes (e.g., Cp'''Ni, CpMo(CO)2) as reaction partners.
• Employing computational analysis and quantum crystallography for mechanistic and structural investigations.

Main Results:

• Successful synthesis of ring-expanded complexes [{LnM}(η3‑Pn3AsCy2][TEF] via arsenium ion bond insertion.
• Identification of ring strain alleviation as the primary driving force for the observed reactivity through computational and crystallographic studies.
• Isolation of related complexes, including arsenium ion coordinated and phosphenium ion inserted species, further validating the reaction pathway.

Conclusions:

• The developed synthetic approach effectively overcomes the challenges in arsenium ion bond insertion.
• Relief of ring strain is a critical factor enabling this challenging reactivity.
• This work expands the scope of pnictenium ion chemistry and provides access to novel organoarsenic compounds.