Fedulin Andrey, Gupta Sandeep K, Rüter Isabelle, Meyer Franc, Jacobi von Wangelin Axel
Department of Chemistry, University of Hamburg, Martin Luther King Pl 6, Hamburg 20146, Germany.
Institute of Inorganic Chemistry, University of Göttingen, Tammannstr. 4, Göttingen 37077, Germany.
Inorg Chem. 2022 Apr 25;61(16):6149-6159. doi: 10.1021/acs.inorgchem.2c00294. Epub 2022 Apr 11.
The combination of pyridonate ligands with transition metal ions enables the synthesis of an especially rich set of diverse coordination compounds involving various κ- and μ-bonding modes and higher nuclearities. With iron(II) ions, this chemical space is rather poorly explored beyond some biomimetic models of the pyridone iron-containing hydrogenase. Here, the topologically new Fe and Fe clusters, Fe(L)[N(SiMe)] () and Fe(L)[N(SiMe)] (), were synthesized (L = 2-pyridonate; L = 6-methyl-2-pyridonate). Complex contained an unprecedented diamondoid Fe@Fe tetrahedron with a central-to-peripheral Fe-Fe distance of ∼3.1 Å. The crystal structure of complex displayed an FeO butterfly motif containing a planar Fe arrangement. Mössbauer spectroscopy confirmed the high-spin ferrous character of all iron ions. SQUID magnetometry reveals that the Fe(II) ions are involved in weak magnetic exchange coupling across the pyridonate bridges that results in antiferromagnetic interactions. The Fe cluster exhibits slow relaxation of magnetization under an applied magnetic field with an effective energy barrier of 38.5 K, rarely observed among the very rare examples of Fe(II) cluster-based single-molecule magnets. Studies of protolytic substitution of the amido ligands demonstrated the lability of the diamondoid Fe core in and the stability of the Fe rhomboid in .
吡啶酮酸盐配体与过渡金属离子的结合能够合成一系列特别丰富多样的配位化合物，这些化合物涉及各种κ键和μ键合模式以及更高的核数。对于铁（II）离子，除了一些含吡啶酮铁的氢化酶的仿生模型外，这个化学空间的探索还相当有限。在此，合成了拓扑结构新颖的铁簇合物Fe(L)[N(SiMe)] （）和Fe(L)[N(SiMe)] （）（L = 2 - 吡啶酮酸盐；L = 6 - 甲基 - 2 - 吡啶酮酸盐）。配合物 包含一个前所未有的类金刚石Fe@Fe四面体，中心到外围的Fe - Fe距离约为3.1 Å。配合物 的晶体结构显示出一个包含平面铁排列的FeO蝶形 motif。穆斯堡尔光谱证实了所有铁离子的高自旋亚铁特性。超导量子干涉仪磁强计表明，Fe(II)离子参与了跨越吡啶酮酸盐桥的弱磁交换耦合，导致反铁磁相互作用。该铁簇合物在施加磁场下表现出磁化的缓慢弛豫，有效能垒为38.5 K，这在基于Fe(II)簇的单分子磁体的极少数例子中很少见。对酰胺配体的质子解取代研究表明，类金刚石Fe核在 中不稳定，而Fe菱形在 中稳定。
