Achieving Room-Temperature Magnetic Coupling between Transition Metals Separated by Over 10 Å: The Role of Spontaneously Generated Triplet Diradicals.

Zhang, Yu; Chen, Zhao; Liu, Xiaofeng; Li, Xiangyang; Li, Xingxing · Nano Lett · 2026

basic_science · Level V

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Abstract

Conventionally, strong magnetic coupling occurs between adjacent transition metals (TMs) with short distances (2-4 Å). Whether it is possible to break this distance limitation and achieve room-temperature magnetic coupling between TMs with nanometer separations (>10 Å) remains an intriguing open question. Here, we propose triplet-diradical-mediated ferromagnetic coupling between widely separated TMs as a promising strategy for achieving room-temperature magnetic ordering. These ligand-centered diradicals, spontaneously generated through TM-to-ligand electron transfer, exhibit large singlet-triplet energy gaps (>2 kcal/mol). First-principles calculations validate this strategy in Mn-based metal-organic frameworks (MOFs), which retain room-temperature magnetic ordering at Mn-Mn distances approaching 18 Å. Electronic structure analysis reveals these MOFs are half-semiconductors and possess symmetry protected topological edge states. This work not only offers a new physical picture for achieving room-temperature magnetic coupling at nanoscale TM-TM distances but also establishes a viable charge-transfer strategy for generating stable diradicals in situ.