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Refinement of anomalous dispersion correction parameters in single-crystal structure determinations

Meurer, Florian; Dolomanov, Oleg V.; Hennig, Christoph; Peyerimhoff, Norbert; Kleemiss, Florian; Puschmann, Horst; Bodensteiner, Michael

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Florian Meurer

Oleg V. Dolomanov

Christoph Hennig

Florian Kleemiss

Michael Bodensteiner


Correcting for anomalous dispersion is part of any refinement of an X-ray dif­fraction crystal structure determination. The procedure takes the inelastic scattering in the diffraction experiment into account. This X-ray absorption effect is specific to each chemical compound and is particularly sensitive to radiation energies in the region of the absorption edges of the elements in the compound. Therefore, the widely used tabulated values for these corrections can only be approximations as they are based on calculations for isolated atoms. Features of the unique spatial and electronic environment that are directly related to the anomalous dispersion are ignored, although these can be observed spectroscopically. This significantly affects the fit between the crystallographic model and the measured intensities when the excitation wavelength in an X-ray diffraction experiment is close to an element's absorption edge. Herein, we report on synchrotron multi-wavelength single-crystal X-ray diffraction, as well as X-ray absorption spectroscopy experiments which we performed on the mol­ecular compound Mo(CO)6 at energies around the molybdenum K edge. The dispersive (f′) and absorptive (f′′) terms of the anomalous dispersion can be refined as independent parameters in the full-matrix least-squares refinement. This procedure has been implemented as a new feature in the well-established OLEX2 software suite. These refined parameters are in good agreement with the independently recorded X-ray absorption spectrum. The resulting crystallographic models show significant improvement compared to those employing tabulated values.


Meurer, F., Dolomanov, O. V., Hennig, C., Peyerimhoff, N., Kleemiss, F., Puschmann, H., & Bodensteiner, M. (2022). Refinement of anomalous dispersion correction parameters in single-crystal structure determinations. IUCrJ, 9(5),

Journal Article Type Article
Acceptance Date Jul 5, 2022
Online Publication Date Jul 20, 2022
Publication Date 2022
Deposit Date Nov 21, 2022
Publicly Available Date Aug 25, 2023
Journal IUCrJ
Publisher International Union of Crystallography
Peer Reviewed Peer Reviewed
Volume 9
Issue 5
Public URL


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