Chen Wei-Ting, Hsu Che-Wei, Lee Jyh-Fu, Pao Chih-Wen, Hsu I-Jui
Department of Molecular Science and Engineering, National Taipei University of Technology, Taipei 10608, Taiwan.
National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
ACS Omega. 2020 Mar 4;5(10):4991-5000. doi: 10.1021/acsomega.9b03887. eCollection 2020 Mar 17.
Iron pentacarbonyl (Fe(CO)) is a versatile material that is utilized as an inhibitor of flame, shows soot suppressibility, and is used as a precursor for focused electron-beam-induced deposition (FEBID). X-ray absorption near-edge structure (XANES) of the K edge, which is a powerful technique for monitoring the oxidation states and coordination environment of metal sites, can be used to gain insight into Fe(CO)-related reaction mechanisms in in situ experiments. We use a finite difference method (FDM) and molecular-orbital-based time-dependent density functional theory (TDDFT) calculations to clarify the Fe K-edge XANES features of Fe(CO). The two pre-edge peaks P and P are mainly the Fe(1s) → Fe-C(σ*) and Fe(1s) → Fe-C(π*) transitions, respectively. When the geometry transformed from to symmetry, a ∼30% decrease of the pre-edge P intensity was observed in the simulated spectra. This implies that the π bonding of Fe and CO is sensitive to changes in geometry. The following rising edge and white line regions are assigned to the Fe(1s) → Fe(4p)(mixing C(2p)) transitions. Our results may provide useful information to interpret XANES spectra variations of in situ reactions of metal-CO or similar compounds with π acceptor ligandlike metal-CN complexes.
五羰基铁（Fe(CO)₅）是一种用途广泛的材料，它被用作火焰抑制剂，具有抑制烟尘的特性，还被用作聚焦电子束诱导沉积（FEBID）的前驱体。K 边的 X 射线吸收近边结构（XANES）是监测金属位点氧化态和配位环境的有力技术，可用于在原位实验中深入了解与 Fe(CO)₅相关的反应机制。我们使用有限差分法（FDM）和基于分子轨道的含时密度泛函理论（TDDFT）计算来阐明 Fe(CO)₅的 Fe K 边 XANES 特征。两个预边峰 P₁ 和 P₂ 分别主要是 Fe(1s) → Fe-C(σ*) 和 Fe(1s) → Fe-C(π*) 跃迁。当几何结构从 转变为 对称时，在模拟光谱中观察到预边 P₁ 强度下降约 30%。这意味着 Fe 与 CO 的 π 键对几何结构变化敏感。随后的上升边和白线区域归因于 Fe(1s) → Fe(4p)(混合 C(2p)) 跃迁。我们的结果可能为解释金属 -CO 或类似化合物与 π 受体配体如金属 -CN 配合物的原位反应的 XANES 光谱变化提供有用信息。
