Lu Zhaohan, Wu Yabei, Wang Zhiyong
Key Laboratory of Advanced Light Conversion Materials and Biophotonics, School of Chemistry and Life Resources, Renmin University of China, Beijing 100872, PR China.
Inorg Chem. 2025 Jul 28;64(29):15292-15300. doi: 10.1021/acs.inorgchem.5c02678. Epub 2025 Jul 11.
Endohedral metallofullerenes Ln@C (Ln = lanthanide) represent a fascinating class of molecular magnets due to their unique single-electron metal-metal bond, which strongly interacts with the 4f electrons of the encapsulated lanthanide atoms. However, a critical limitation arises from their unstable triplet ground state, which complicates experimental isolation and practical utilization. To address this challenge, we propose an endohedral doping strategy by introducing a third metal atom (M = group IA or IIIA metal) to form mixed-metal fullerenes GdM@C. Unlike previous approaches that rely on exohedral functionalization or cage modification, our method preserves the pristine -C structure. Our computational studies reveal strong intramolecular magnetic couplings in these metallofullerenes, with the coupling strength showing tunability based on the ionic radius of M. Notably, the GdK@C metallofullerene exhibits the largest reported coupling constant among metallofullerenes (+238 cm). A detailed bonding analysis uncovers distinct electronic structures, depending on the dopant: IA metals (Li, Na, and K) form a delocalized three-center-one-electron (3c-1e) bond across the Gd-Gd-M cluster, while IIIA metals (Al, Ga, and In) exhibit a 2c-1e Gd-Gd bond coexisting with a 3c-2e bond involving the IIIA atom. This work establishes an innovative approach to stabilize redox-active Ln@C systems while remarkably enhancing their intrinsic magnetic characteristics.
内嵌金属富勒烯Ln@C（Ln = 镧系元素）由于其独特的单电子金属 - 金属键而成为一类引人入胜的分子磁体，该键与封装的镧系原子的4f电子强烈相互作用。然而，它们不稳定的三重态基态带来了一个关键限制，这使得实验分离和实际应用变得复杂。为应对这一挑战，我们提出了一种内嵌掺杂策略，即引入第三种金属原子（M = IA族或IIIA族金属）以形成混合金属富勒烯GdM@C。与以往依赖于外表面功能化或笼修饰的方法不同，我们的方法保留了原始的 -C结构。我们的计算研究揭示了这些金属富勒烯中存在强分子内磁耦合，耦合强度基于M的离子半径表现出可调性。值得注意的是，GdK@C金属富勒烯在金属富勒烯中表现出报道的最大耦合常数（+238 cm）。详细的键合分析揭示了不同的电子结构，这取决于掺杂剂：IA族金属（Li、Na和K）在Gd - Gd - M簇上形成离域的三中心单电子（3c - 1e）键，而IIIA族金属（Al、Ga和In）表现出一个2c - 1e的Gd - Gd键与一个涉及IIIA原子的3c - 2e键共存。这项工作建立了一种创新方法，用于稳定氧化还原活性的Ln@C系统，同时显著增强其固有磁特性。
