Synthesis, Structure and Electronic Properties of a Stable π‐Type 3‐Electron‐2‐Center‐Bonded Species: A Silicon Analogue of a Bicyclo[1.1.0]butane Radical Anion
Synthesis, Structure and Electronic Properties of a Stable π‐Type 3‐Electron‐2‐Center‐Bonded Species: A Silicon Analogue of a Bicyclo[1.1.0]butane Radical Anion
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稳定π型3-电子-2-中心键合物质的合成、结构和电子性质：双环[1.1.0]丁烷自由基阴离子的硅类似物
DOI：
10.1002/anie.202117584
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Iwamoto Takeaki
中科院分区：
文献类型：
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作者：
Koike Taichi;Osawa Raiki;Ishida Shintaro;Iwamoto Takeaki
σ-型3电子2中心（3e-2c）键作为自由基化学和一些生物体系中的关键键合基序之一已被广泛研究。然而，包含3e-2c π-键而没有潜在的σ-键框架的“π-型3e-2c-键物种”迄今为止在理论和实验上都没有被探索。在这里，我们报告了第一个稳定的π-型3e-2c-键合物种的合成，一个硅类似物的双环[1.1.0]丁烷自由基阴离子。该化合物具有极长的桥头Si−Si键（3.0638（8）π）和溶液中922 nm处的强近红外吸收，这是由HOMO→SOMO [π（Si−Si）→π*（Si−Si）]跃迁引起的。 DFT计算揭示了两个桥头硅原子之间的π-型成键相互作用，其中未成对电子主要在相应的π*-型轨道上离域，这为构建π-电子系统引入了新的成键基序。
σ‐Type 3‐electron‐2‐center (3e‐2c) bonds have been extensively studied as one of the key bonding motifs in radical chemistry and some biological systems. “π‐Type 3e‐2c‐bonded species” that contain a 3e‐2c π‐bond without an underlying σ‐bond framework, however, have been unexplored so far both theoretically and experimentally. Herein, we report the synthesis of the first stable π‐type 3e‐2c‐bonded species, a silicon analogue of a bicyclo[1.1.0]butane radical anion. This compound exhibits an extremely long bridgehead Si−Si bond (3.0638(8) Å) and a strong near‐IR absorption at 922 nm in solution which arises from a HOMO→SOMO [π(Si−Si)→π*(Si−Si)] transition. DFT calculations revealed a π‐type bonding interaction between the two bridgehead silicon atoms with an unpaired electron mainly delocalized across the corresponding π*‐type orbital, which introduces a novel bonding motif for constructing π‐electron systems.