Diederich Tim Marcel, Wehland Tim, Schrodt Maximilian, Kochetov Nikolai, Schnegg Alexander, Jimenez-Muñoz Carlos M, Krewald Vera, Ni Lingmei, Salas Nicole Segura, Kramm Ulrike I, Ballmann Joachim, Enders Markus
Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
Max Planck Institute for Chemical Energy Conversion, 45470, Mülheim an der Ruhr, Germany.
Chemistry. 2025 Jul 11;31(39):e202501474. doi: 10.1002/chem.202501474. Epub 2025 Jun 18.
The electronic and magnetic properties of ferrous iron in the iron(II)-2,3,9,10,16,17,23,24-octakis(2,6-diisopropylphenoxy)phthalocyanine (FePc), exhibiting a true square-planar molecular environment, are investigated. Inhibition of intermolecular interactions by steric substituents allows detailed investigation of the electronic structure arising from the planar geometry of the d electron configuration. Complementary magnetometry, Mössbauer, FD-FT THz-EPR (frequency-domain Fourier-transform terahertz electron paramagnetic resonance) and pNMR (nuclear magnetic resonance of paramagnetic molecules) spectroscopies show that FePc has an S = 1 ground state with large positive axial zero-field splitting (ZFS) and a strongly anisotropic g-tensor, with two g-values much larger than the free electron g-value and one smaller. Correlation between the magnetic properties and the electronic structure is provided by high-level quantum chemical calculations. The calculations indicate a nearly triply degenerate ground level, in which spin-orbit coupling mixes the isolated A ground state with two excited E states, whose energy gaps to the ground state are almost identical. These findings provide valuable insights in the electronic structure of iron phthalocyanines and the long-standing discussion on their true electronic ground level, which has important implications for the application of this important class of complexes in catalysis and magnetic materials.
研究了处于铁（II）-2,3,9,10,16,17,23,24-八（2,6-二异丙基苯氧基）酞菁（FePc）中具有真正平面正方形分子环境的亚铁离子的电子和磁性特性。空间取代基对分子间相互作用的抑制作用使得能够详细研究由d电子构型的平面几何结构产生的电子结构。辅助的磁测量、穆斯堡尔谱、频域傅里叶变换太赫兹电子顺磁共振（FD-FT THz-EPR）和顺磁分子的核磁共振（pNMR）光谱表明，FePc具有S = 1的基态，具有大的正轴向零场分裂（ZFS）和强烈各向异性的g张量，其中两个g值远大于自由电子的g值，一个较小。高水平量子化学计算提供了磁性与电子结构之间的相关性。计算表明存在一个近乎三重简并的基态能级，其中自旋轨道耦合将孤立的A基态与两个激发的E态混合，这两个激发态与基态的能隙几乎相同。这些发现为酞菁铁的电子结构以及关于其真正电子基态的长期讨论提供了有价值的见解，这对于这类重要配合物在催化和磁性材料中的应用具有重要意义。
