Theoretical Analysis of Fe K-Edge XANES on Iron Pentacarbonyl
Wei‐Ting Chen, Che-Wei Hsu, Jyh‐Fu Lee, Chih‐Wen Pao, I‐Jui Hsu
Abstract
High Resolution Image Download MS PowerPoint Slide Iron pentacarbonyl (Fe(CO) 5 ) 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) 5 -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) 5 . The two pre-edge peaks P 1 and P 2 are mainly the Fe(1s) → Fe–C(σ*) and Fe(1s) → Fe–C(π*) transitions, respectively. When the geometry transformed from D 3 h to C 4 v symmetry, a ∼30% decrease of the pre-edge P 2 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.