Metal-centred planar [15]annulenes

• 成果类型: Article
• 署名作者: Xu, Binbin; Chen, Dafa; Ruan, Kaidong; Luo, Ming; Cai, Yuanting; Qiu, Jia; Zhou, Wenhao; Cao, Bula; Lin, Zhenyang; Sessler, Jonathan L.; Xia, Haiping
• 署名单位: Southern University of Science & Technology; Southern University of Science & Technology; Hong Kong University of Science & Technology; University of Texas System; University of Texas Austin
• 刊物名称: Nature
• ISSN/ISSBN: 0028-1429
• DOI: 10.1038/s41586-025-08841-2
• 发表日期: 2025-05-01
• 关键词: crystal-structures; complexes; aromaticity; bond

摘要

The discovery of ferrocene1 heralded the advent of modern organometallic chemistry. Characterized by the pi-coordination of a metal by one or two planar annulene anions, ferrocenes and their analogues2, 3-4 exemplify the archetype of out-of-plane annulene metal complexes. By contrast, the integration of metal within the annulene core to form in-plane annulene metal complexes featuring metal-carbon sigma bonds has been obstructed not only by the synthetic difficulty and the non-planarity of annulenes with appropriate internal dimensions, but also by the difficulty of embedding the metal. These challenges have prevented the isolation of such in-plane annulene metal complexes. Here we report the preparation of three metal-centred planar [15]annulene frameworks. The most symmetrical fragment has D5h symmetry, with the metal centre shared by five identical five-membered rings. Density functional theory calculations demonstrate that metal d orbitals participate in conjugation with these five-membered rings, rendering all of them aromatic. The overall framework bears a loose structural and spectroscopic analogy to metallo-expanded porphyrins with multiple aza donors5, which thus provides a nexus between annulene chemistry and classic heteroatom-based coordination chemistry. The present systems display high stability and are easily functionalized. We thus suggest that metal-centred planar annulenes could emerge as promising building blocks for materials science.