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02/15/2017 Chemistry Guest Lecture - Prof. Simon Grabowsky/Dr. Ponomarenko

Electron-Density Correlation

Wednesday, February 15, 2017 - 16:00
Lecture Hall - Research III
Chemistry Guest Lecture by:
Prof. Dr. Simon Grabowky - Universität Bremen - Institut für Anorganische Chemie und Kristallographie
Dr. Maksym Ponomarenko - Jacobs University Bremen gGmbH
Maksym Ponomarenko/Simon Grabowsky

In structure correlation,[1] crystallographic structures with systematically varying substituents or different crystalline environments are used as snapshots for a chemical reaction or dynamic process. E.g., the Bürgi-Dunitz angle of attack of a nucleophile at a carbonyl group has been defined using this technique.[2] Normally, two geometric properties such as bond distances or angles are correlated with each other to simulate a pseudo-reaction pathway. We have adopted this technique to elucidate the mechanism of nucleophilic substitution at silicon, and we use penta-coordinated silicon compounds (Figure) upon systematic variation of one of the substituents.
In our work, we correlate the N…Si with the Si-X bond, but not only in terms of bond distances, but also in terms of experimental electron-density and real-space bonding indicators, hence the new term “electron-density correlation” instead of “structure correlation”. This requires high-quality crystals and high-resolution low-temperature synchrotron X-ray diffraction experiments. We will report on the experimental difficulties and successes during synthesis and measurement, and present first preliminary results on the correlation studies.

[1] H.-B. Bürgi, Structure Correlation, VCH, 1994.
[2] H. B. Bürgi, J. D. Dunitz, J. M. Lehn, G. Wipff: Stereochemistry of reaction paths at carbonyl centres. Tetrahedron 1974, 30 (12), 1563–1572.

Prof. Dr. Gerd-Volker Röschenthaler | Professor of Chemistry | Focus Area: Health
Department of Life Sciences & Chemistry
Email:  g.roeschenthaler [at] (subject: Guest%20Chemistry%20Lecture%2C%20February%2015th%2C%202017)  | Tel: +49 421 200-3138