Electrophilic As-functionalisation of σ-arsolido complexes

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Molybdenum Complexes

Background:

• The chemistry of σ-arsolido complexes, particularly their reactivity and synthetic utility, remains an area of active investigation.
• Understanding the behavior of arsenic-containing ligands in transition metal complexes is crucial for developing new catalytic and materials applications.

Purpose of the Study:

• To investigate the alkylation reactions of molybdenum-arsolido complexes with various alkylating agents.
• To explore the reactivity of these complexes with activated alkynes.
• To characterize the resulting products and elucidate reaction mechanisms.

Main Methods:

• Synthesis and characterization of molybdenum-arsolido complexes.
• Alkylation reactions using methyl triflate (MeOTf) and iodomethane (MeI).
• Reactions with activated alkynes (e.g., CF3C≡CCF3, MeO2CC≡CCO2Me).
• Spectroscopic techniques (NMR, X-ray crystallography) for product identification.

Main Results:

• Alkylation of [Mo(AsC4Me4)(CO)3(η5-C5H5)] with MeOTf yields the pentamethylarsole complex [Mo(MeAsC4Me4)(CO)3(η5-C5H5)](OTf).
• Reaction with MeI leads to a complex mixture of products, including alkylated arsenic species and molybdenum-containing fragments.
• The arsole ligand can be readily liberated from the complex.
• Reactions with activated alkynes do not follow a [4+2] cycloaddition pathway but proceed via electrophilic attack at arsenic, forming spirocyclic complexes with carbonyl ligand incorporation.

Conclusions:

• Molybdenum-arsolido complexes exhibit diverse reactivity towards alkylating agents and activated alkynes.
• The observed reactions provide new synthetic routes to functionalized arsole ligands and novel organometallic architectures.
• The formation of spirocyclic complexes highlights a unique reaction pathway involving electrophilic attack and metallacyclisation.