Atak Kaan, Golnak Ronny, Xiao Jie, Pflüger Mika, Brandenburg Tim, Winter Bernd, Aziz Emad F
Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany.
Phys Chem Chem Phys. 2015 Feb 7;17(5):3409-14. doi: 10.1039/c4cp04703f. Epub 2014 Dec 22.
The local electronic structure of the cobalt centre-ion of Co(III) protoporphyrin IX chloride dissolved in dimethyl sulfoxide (DMSO) liquid solution is studied by resonant inelastic X-ray scattering (RIXS) spectroscopy at the cobalt L-edge. The resulting cobalt 2p partial-fluorescence-yield (PFY) X-ray absorption (XA) spectrum, integrated from RIXS spectra, is simulated for various possible spin-states and coordination of the cobalt centre by using the newly developed density functional theory/restricted open shell single excitation configuration interaction (DFT/ROCIS) method. Comparison between experiment and calculation shows that the cobalt ion (3d(6) electronic configuration) adopts a low-spin state with all six 3d electrons paired, and the cobalt centre is either 5-coordinated by its natural ligands (one chloride ion and four nitrogen atoms), or 6-coordinated, when binding to an oxygen atom of a DMSO solvent molecule. Analysis of the measured RIXS spectra reveals weak 3d-3d electron correlation, and in addition a value of the local HOMO-LUMO gap at the Co sites is obtained.
通过在钴L边的共振非弹性X射线散射（RIXS）光谱，研究了溶解于二甲基亚砜（DMSO）液体溶液中的氯化钴（III）原卟啉IX中心离子的局部电子结构。利用新开发的密度泛函理论/受限开壳单激发组态相互作用（DFT/ROCIS）方法，对从RIXS光谱积分得到的钴2p部分荧光产率（PFY）X射线吸收（XA）光谱，针对钴中心的各种可能自旋态和配位情况进行了模拟。实验与计算结果的比较表明，钴离子（3d(6)电子构型）采用低自旋态，所有六个3d电子成对，钴中心要么由其天然配体（一个氯离子和四个氮原子）进行五配位，要么在与DMSO溶剂分子的一个氧原子结合时进行六配位。对测量的RIXS光谱的分析揭示了弱的3d - 3d电子相关性，此外还获得了钴位点处的局部最高占据分子轨道 - 最低未占据分子轨道能隙值。
