Hunger David, Netz Julia, Suhr Simon, Thirunavukkuarasu Komalavalli, Engelkamp Hans, Fåk Björn, Albold Uta, Beerhues Julia, Frey Wolfgang, Hartenbach Ingo, Schulze Michael, Wernsdorfer Wolfgang, Sarkar Biprajit, Köhn Andreas, van Slageren Joris
Institute of Physical Chemistry, University of Stuttgart, Stuttgart, Germany.
Institute of Theoretical Chemistry, University of Stuttgart, Stuttgart, Germany.
Nat Commun. 2025 Mar 4;16(1):2157. doi: 10.1038/s41467-025-57210-0.
Metal-organic compounds that feature magnetic bistability have been proposed as bits for magnetic storage, but progress has been slow. Four-coordinate cobalt(II) complexes feature high inversion barriers of the magnetic moment, but they lack magnetic bistability. Developing radical-bridged polynuclear systems is a promising strategy to encounter this; however detailed investigations of such species are scarce. We report an air-stable radical-bridged dinuclear cobalt(II) complex, studied by a combination of magnetometry and spectroscopy. Fits of the data give D = -113 cm for the zero-field splitting (ZFS) and J = 390 cm for the metal-radical exchange. Ab initio investigations reveal first-order spin-orbit coupling of the quasi-degenerate and d orbitals to be at the heart of the large ZFS. The corresponding transitions are spectroscopically observed, as are transitions related to the exchange coupling. Finally, signatures of spin-phonon coupling are observed and theoretically analyzed. Furthermore, we demonstrate that the spectral features are not predominantly spin excitations, but largely vibrational in character.
具有磁双稳性的金属有机化合物已被提议作为磁存储的位元，但进展缓慢。四配位钴（II）配合物具有较高的磁矩反转势垒，但缺乏磁双稳性。开发自由基桥连多核体系是解决这一问题的一种有前景的策略；然而，对此类物种的详细研究却很少。我们报道了一种空气稳定的自由基桥连双核钴（II）配合物，通过磁力测量和光谱学相结合的方法进行了研究。数据拟合给出零场分裂（ZFS）的D = -113 cm和金属-自由基交换的J = 390 cm。从头算研究表明，准简并的 和d轨道的一阶自旋-轨道耦合是大ZFS的核心。相应的跃迁在光谱上被观察到，与交换耦合相关的跃迁也是如此。最后，观察到了自旋-声子耦合的特征并进行了理论分析。此外，我们证明光谱特征并非主要是自旋激发，而是在很大程度上具有振动特征。
