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Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
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Planar Tetracoordinate Silicon in Organic Molecules As Carbenoid-Type Amphoteric Centers: A Computational Study
Yuwei Zhang1, Caiyun Zhang1, Yirong Mo2
1State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian, Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemistry Engineering, Xiamen University, 422 Siming Rd., Xiamen, 361005, China.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|October 26, 2020
Summary
Chemists designed stable planar tetracoordinate silicon (ptSi) compounds. These aromatic molecules exhibit unique carbenoid behaviors and tunable properties, paving the way for novel silicon chemistry.
Area of Science:
- Computational chemistry
- Materials science
- Inorganic chemistry
Background:
- Synthesizing stable compounds with planar tetracoordinate silicon (ptSi) centers is a significant challenge.
- Existing aromaticity rules may not apply to complex, fused ring systems.
Purpose of the Study:
- To theoretically design and computationally verify novel aromatic ptSi compounds.
- To investigate the stability and electronic properties of these designed compounds.
- To explore the potential for tuning the reactivity of the central silicon atom.
Main Methods:
- Theoretical design of ptSi compounds with fused conjugated rings.
- Born-Oppenheimer molecular dynamics (BOMD) simulations for stability assessment.
- Potential energy surface scanning to confirm stability.
- Bonding analyses to understand electronic structure and stabilization mechanisms.
Main Results:
- Successfully designed and verified a series of stable aromatic ptSi compounds.
- Identified Si-16-5555 (SiN4C8H8) with 16π electrons as particularly stable under ambient conditions.
- Demonstrated that Hückel's rule is insufficient for predicting aromaticity in these fused systems.
- Revealed strong electron donation stabilizing the ptSi center and planar aromaticity.
- Observed carbenoid-type behaviors due to partial occupation of the Si 3pz orbital.
Conclusions:
- The designed ptSi compounds are stable and likely exist under standard conditions.
- The stabilization mechanism involves electron donation from peripheral rings to the central silicon.
- The central silicon atom exhibits amphoteric, carbenoid-like properties.
- Tunable electronic properties of the ptSi center can be achieved by modifying substituent groups.
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