Radović Aleksa, Henthorn Justin T, Wang Hongxin, Prajapat Deepak, Sergeev Ilya, Nagasawa Nobumoto, Yoda Yoshitaka, Cramer Stephen P, Cutsail George E
Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr, Germany.
School of Chemistry, University College Dublin, Dublin, Ireland.
Nat Commun. 2025 Jul 25;16(1):6843. doi: 10.1038/s41467-025-62118-w.
Iron-sulfur clusters fulfill numerous roles throughout biology. The reduced [2Fe-2S] cluster offers unique electronic and magnetic properties due to its mixed-valent nature and can serve as an essential model for understanding electron transfer, electron delocalization, and accessible spin states not only in mixed-valent dimers, but potentially larger iron sulfur clusters. Recently a series of mixed-valent diiron dichalcogenide complexes [LFeQ] (Q = S (1), Se (2), Te (3), L = 2,6-diisopropylphenyl β-diketiminate ligand) were synthesized and characterized, where complex 1 showed a typical S = 1/2 spin state, while complexes 2 and 3 exhibited intermediate S = 3/2 spin states, potentially enabled by the minimization of vibronic coupling. Here we studied the vibrational dynamics of the Fe and Te centers in these complexes using Fe and Te nuclear resonance vibrational spectroscopy (NRVS), coupled with DFT calculations. The findings suggest that heavy character of larger chalcogen atoms results in decreased vibronic coupling. The observation of an intermediate spin state is shown to be unattainable for lighter FeQ cores. This highlights the crucial role of vibronic coupling in modulating the electronic structure of mixed-valence systems and should enhance understanding of the electronic structure in more complex biological Fe-S clusters.
铁硫簇在整个生物学中发挥着多种作用。还原态的[2Fe-2S]簇由于其混合价态性质而具有独特的电子和磁性特性，不仅可以作为理解混合价二聚体中电子转移、电子离域和可及自旋态的重要模型，还可能适用于更大的铁硫簇。最近合成并表征了一系列混合价二铁二硫属化合物配合物[LFeQ]（Q = S (1)、Se (2)、Te (3)，L = 2,6-二异丙基苯基β-二酮亚胺配体），其中配合物1表现出典型的S = 1/2自旋态，而配合物2和3表现出中间的S = 3/2自旋态，这可能是通过最小化振动耦合实现的。在这里，我们使用铁和碲核共振振动光谱（NRVS）并结合密度泛函理论计算，研究了这些配合物中铁和碲中心的振动动力学。研究结果表明，较大硫属原子的重原子特性导致振动耦合降低。结果表明，对于较轻的FeQ核，无法观察到中间自旋态。这突出了振动耦合在调节混合价体系电子结构中的关键作用，并应有助于加深对更复杂生物铁硫簇电子结构的理解。
