Facile C-H Bond Metathesis Mediated by a Stannylene

Area of Science:

• Organometallic Chemistry
• Main group chemistry
• Radical chemistry

Background:

• Diarylstannylenes are reactive low-valent tin compounds.
• C-H activation and functionalization are key transformations in synthetic chemistry.
• Understanding the reactivity of low-valent main group compounds is crucial for developing new synthetic methodologies.

Purpose of the Study:

• To investigate the C-H metathesis reactivity of a diarylstannylene, :Sn(Ar^iPr4)₂.
• To characterize the products of the C-H metathesis reaction.
• To explore the potential for radical formation during the reaction.

Main Methods:

• Reactions were conducted in toluene, m-xylene, or mesitylene solutions at 80 °C.
• Products were characterized using ¹H, ¹³C, and ¹¹⁹Sn NMR, UV-vis, and IR spectroscopy.
• X-ray crystallography was used to determine the structures of key products.
• Electron paramagnetic resonance (EPR) spectroscopy was employed to detect radical species.

Main Results:

• The diarylstannylene :Sn(Ar^iPr4)₂ successfully underwent C-H metathesis with toluene, m-xylene, and mesitylene.
• New organotin compounds, [Ar^iPr4Sn(CH₂Ar)]₂, were synthesized and characterized.
• A stoichiometric amount of the arene Ar^iPr4H was produced, indicating a C-H bond cleavage mechanism.
• EPR spectroscopy revealed the formation of a novel one-coordinate, tin-centered radical, :ṠnAr^iPr4, resulting from Sn-C bond cleavage.

Conclusions:

• Diarylstannylenes are capable of mediating C-H metathesis reactions with arenes.
• The reaction proceeds via Sn-C bond cleavage, leading to the formation of organotin products and a unique tin-centered radical.
• This study expands the known reactivity of low-valent organotin compounds and highlights a new pathway for generating tin radicals.