An Open-Shell Singlet Sn^I  Diradical and H₂  Splitting.

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Materials Science

Background:

• Exploration of low-valent main group compounds is crucial for understanding unique bonding and reactivity.
• Anionic dicarbene ligands offer versatile platforms for stabilizing unusual oxidation states in main group elements.
• The synthesis and characterization of novel organotin compounds can lead to new materials and catalytic applications.

Purpose of the Study:

• To synthesize and characterize the first tin(I) diradical stabilized by an anionic dicarbene ligand.
• To investigate the electronic structure and aromaticity of the resulting tin-containing ring system.
• To explore the reactivity of the novel tin(I) diradical, particularly its ability to cleave small molecules.

Main Methods:

• Synthesis of the tin(I) diradical via KC8 reduction of a bis-chlorostannylene precursor.
• Characterization using X-ray crystallography, DFT, and CASSCF calculations to determine electronic structure and diradical character.
• Reactivity studies including hydrogen molecule splitting and reactions with electrophilic reagents (PhSeSePh, MeOTf).

Main Results:

• Isolation of the first Sn(I) diradical, [(ADCPh)Sn]2, as a green crystalline solid.
• The compound features a six-membered C4Sn2 ring exhibiting a diatropic ring current, classifying it as a 1,4-distannabenzene derivative.
• Computational studies reveal an open-shell singlet ground state with a small singlet-triplet energy gap and significant diradical character (37%).
• The tin(I) diradical readily cleaves H2 at room temperature, forming a bis-hydridostannylene.

Conclusions:

• The successful synthesis and characterization of [(ADCPh)Sn]2 represent a significant advancement in the chemistry of low-valent organotin compounds.
• The compound's 1,4-distannabenzene nature and diradical character open new avenues for exploring aromaticity and reactivity in main group chemistry.
• The observed H2 splitting reactivity highlights the potential of this tin(I) diradical as a reagent in small molecule activation.