Authentic Sn═B-Double Bonds in Polar Stannaborene Derivatives

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Synthetic Chemistry

Background:

• The synthesis of stable compounds featuring multiple bonds between heavier main group elements remains a significant challenge.
• Tin-boron compounds are of interest due to their unique electronic properties and potential applications.

Purpose of the Study:

• To synthesize and characterize novel tin-boron compounds with a Sn═B double bond.
• To investigate the reactivity of these new compounds, particularly stannaborenium cations.

Main Methods:

• Oxidative addition of boron tribromide to a stannylene-phosphine Lewis pair.
• Reduction of intermediate compounds using magnesium or hydride substitution.
• Isolation and characterization of stannaborene anions and stannaborenium cations using weakly coordinating anions.
• Reaction of the stannaborenium cation with ammonia.

Main Results:

• Successful synthesis of an authentic Sn═B-moiety in stannaborenyl anions and stannaborenium cations.
• Characterization of a Grignard-type stannaborene with a Sn═B double bond and a B-Mg interaction.
• Isolation of a phosphine and N-heterocyclic carbene (NHC)-stabilized stannaborenium cation.
• Observation of ammonia addition to the stannaborenium cation, resulting in Sn-NH2 and B-H bond formation.

Conclusions:

• The study demonstrates the successful synthesis and characterization of compounds containing the elusive Sn═B double bond.
• The synthesized stannaborenium cation exhibits interesting reactivity, undergoing addition reactions with small molecules like ammonia.
• These findings expand the scope of known tin-boron chemistry and open avenues for further investigations into related systems.