Co(III) protoporphyrin IX chloride in solution: spin-state and metal coordination revealed from resonant inelastic X-ray scattering and electronic structure calculations
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Updated: Apr 19, 2026
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Kaan Atak1, Ronny Golnak, Jie Xiao
1Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany. emad.aziz@helmholtz-berlin.de.
Abstract:
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.
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