Stable Push-Pull Disilene: Substantial Donor-Acceptor Interactions through the Si═Si Double Bond

Area of Science:

• Organosilicon Chemistry
• Materials Science
• Photophysics

Background:

• The push-pull effect is a well-established strategy for tuning the electronic properties of π-electron systems.
• Disilenes, silicon analogs of alkenes featuring a Si═Si double bond, are less explored compared to their carbon counterparts.
• Understanding the electronic behavior of substituted disilenes is crucial for developing novel silicon-based materials.

Purpose of the Study:

• To synthesize and characterize the first push-pull disilene, incorporating amino and boryl substituents.
• To investigate the electronic interactions between the Si═Si double bond and the push-pull substituents.
• To explore the reactivity of the push-pull disilene with molecular hydrogen.

Main Methods:

• Synthesis of 1-amino-2-boryldisilene (1) via established organosilicon synthetic routes.
• Spectroscopic analysis (UV-Vis absorption, NMR) to determine electronic and structural properties.
• X-ray crystallography to elucidate the molecular structure and bonding.
• Reactivity studies involving treatment with H2 gas.

Main Results:

• Successful synthesis and characterization of 1-amino-2-boryldisilene, the first push-pull disilene.
• Spectroscopic and structural data reveal significant electronic communication between the Si═Si bond and the amino/boryl groups.
• A notable red-shift in the π → π* absorption band of (1) compared to an alkyl-substituted disilene (2) indicates enhanced conjugation.
• Treatment of (1) with H2 leads to the cleavage of two H2 molecules, forming a trihydridodisilane and hydroborane.

Conclusions:

• The study demonstrates the successful implementation of the push-pull strategy in disilene chemistry.
• The findings highlight the tunable electronic properties of disilenes through substituent effects.
• The observed reactivity with H2 suggests potential applications in catalysis or materials transformation.