Distannabarrelenes with Three Coordinated Sn^II Atoms

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Coordination Chemistry

Background:

• Anionic dicarbenes are versatile ligands in organometallic chemistry.
• Tin compounds with low oxidation states are of interest due to their unique electronic properties.

Purpose of the Study:

• To synthesize and characterize novel 1,4-distannabarrelene compounds.
• To investigate the reactivity of these compounds with chalcogens.
• To explore the electronic structure of the synthesized compounds.

Main Methods:

• Synthesis of crystalline 1,4-distannabarrelene compounds from anionic dicarbenes.
• Characterization using Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray diffraction.
• Density Functional Theory (DFT) calculations to determine electronic properties.

Main Results:

• Successful synthesis of crystalline 1,4-distannabarrelene compounds [(ADCAr)3Sn2]SnCl3 (3-Ar).
• Characterization confirmed the barrelene framework with three coordinated Sn(II) atoms and an SnCl3 anionic unit.
• DFT calculations indicated the Highest Occupied Molecular Orbital (HOMO) is primarily located on the Sn(II) atoms of the barrelene unit.
• Reaction with sulfur and selenium yielded mixed-valence Sn(II)/Sn(IV) compounds.

Conclusions:

• The synthesized 1,4-distannabarrelene compounds represent a novel class of organotin structures.
• The electronic structure is dominated by the lone pair on the Sn(II) atoms within the barrelene framework.
• These compounds serve as precursors for synthesizing mixed-valence tin chalcogenides.