Aspherical-atom modeling of coordination compounds by single-crystal X-ray diffraction allows the correct metal atom to be identified.
Single-crystal X-ray diffraction (XRD) is often considered the gold standard in analytical chemistry, as it allows element identification as well as determination of atom connectivity and the solid-state structure of completely unknown samples. Element assignment is based on the number of electrons of an atom, so that a distinction of neighboring heavier elements in the periodic table by XRD is often difficult. A computationally efficient procedure for aspherical-atom least-squares refinement of conventional diffraction data of organometallic compounds is proposed. The iterative procedure is conceptually similar to Hirshfeld-atom refinement (Acta Crystallogr. Sect. A- 2008, 64, 383-393; IUCrJ. 2014, 1,61-79), but it relies on tabulated invariom scattering factors (Acta Crystallogr. Sect. B- 2013, 69, 91-104) and the Hansen/Coppens multipole model; disordered structures can be handled as well. Five linear-coordinate 3d metal complexes, for which the wrong element is found if standard independent-atom model scattering factors are relied upon, are studied, and it is shown that only aspherical-atom scattering factors allow a reliable assignment. The influence of anomalous dispersion in identifying the correct element is investigated and discussed.
Institut für Anorganische und Angewandte Chemie, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, 37077 Göttingen (Germany). birger.dittrich@chemie.uni-hamburg.de.
Birger
B
Dittrich
Claudia M
CM
Wandtke
Alke
A
Meents
Kevin
K
Pröpper
Kartik Chandra
KC
Mondal
Prinson P
PP
Samuel
Nurul
N
Amin Sk
Amit Pratap
AP
Singh
Herbert W
HW
Roesky
Navdeep
N
Sidhu
X-ray diffraction; anomalous dispersion; carbenes; coordination compounds; density functional calculations