Silicon cyclopentadienides featuring a nonplanar 6π aromatic Si5 ring

• 成果类型: Article
• 署名作者: Iwamoto, Takeaki; Ishikawa, Tomoki; Ishida, Shintaro
• 署名单位: Tohoku University
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-8075; 1095-9203
• DOI: 10.1126/science.aed0168
• 发表日期: 2026-02-05
• 关键词: PI-BOND ENERGY; ORGANOSILICON COMPOUNDS; reactivity; complexes; chemistry; compound; LI12SI7; analogs; cation; route

摘要

Compared with the wide variety of reports on carbon pi-electron compounds, the silicon counterparts remain scarce because of the intrinsic preference of silicon to form sigma-bonded compounds. In particular, silicon compounds in which pi-electrons are delocalized over five or more silicon atoms have been elusive. We report the synthesis of pentasilicon analogs of cyclopentadienides (pentasilacyclopentadienides). These compounds contain nonplanar five-membered silicon rings with some pyramidalized silicon atoms and uneven silicon-silicon distances. The highly shielded 7Li nuclear magnetic resonance signal of a lithium pentasilacyclopentadienide corroborates the presence of a diamagnetic ring current in the five-membered ring, which is indicative of at least some degree of aromaticity. Furthermore, a computational study revealed that bulky substituents and the delocalization of pi-electrons stabilize the pentasilacyclopentadienide structure.