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Croatian Association of Crystallographers

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Bijenička c. 54

HR-10000 Zagreb

Croatia

What a synthetic chemist learns from charge density

Dietmar Stalke, Institut für Anorganische Chemie der Universität Göttingen,

Tammannstraße 4, 37077 Göttingen, Germany; dstalke@chemie.uni-goettingen.de

From the knowledge of the distancies at the atomic level and the arrangement in the solid phase many properties, both at the molecular and macroscopic scale, can be deduced. However, the most basic concept, the chemical bond and reactivity, is still vigorously discussed. Still there is room for interpretation, because single crystal structural analyses based on the independent atom model only provides the positions of the centroids of the atoms and the distances between the atoms. In the electron density maps there are no lines or dashes defining or even indicating the chemical bond and the nature of the bonding remains a matter of interpretation based on a bonding model. Hence the anecdote that a bond is where the chemist draws the line remains valid to a certain extent. Most of our understanding of the chemical bond is still deduced from the distances and angles, which are determined as a result of the crystallographic analysis and reactivity is introduced on this basis.[1] Various topics are addressed in the talk and connected to reactivity:

1) The concept of “hypervalency” is not only dispensable but also obscuring new synthetic approaches. This is discussed with the S=N, S=O and P=N “double” bonds.[2]

2) Aromaticity is one of the fuzziest concepts in chemistry. Attempted clearance is provided with (RSi)₆ [3] and bis(thiozolyl)phosphane.[4]

3) “Hypervalency” is accompanied by “hypovalency”, hence low-valent Group 14 species will be discussed.[5]

[1] review: D. Stalke, Chem. Eur. J. 2011, 48, 9559-9573.

[2] M. S. Schmøkel, S. Cenedese, J. Overgaard, M. R. V. Jørgensen, Y.-S. Chen, C. Gatti, D. Stalke, B. B. Iversen, Inorg. Chem. 2012, 51, 8607-8616.

[3] D. Kratzert, D. Leusser, J. J. Holstein, B. Dittrich, K. Abersfelder, D. Scheschkewitz, D. Stalke, Angew. Chem. 2013, 125, 4574-4578; Angew. Chem. Int. Ed. 2013, 52, 4478-4482.

[4] J. Henn, K. Meindl, A. Oechsner, G. Schwab, T. Koritsanszky, D. Stalke, Angew. Chem. 2010, 122, 2472-2476; Angew. Chem. Int. Ed. 2010, 49, 2422-2426.

[5] K. C. Mondal, H. W. Roesky, M. C. Schwarzer, G. Frenking, S. Neudeck, I. Tkach, H. Wolf, D. Kratzert, R. Herbst-Irmer, B. Niepötter, D. Stalke, Angew. Chem. 2013, 125, 3036-3040; Angew. Chem. Int. Ed. 2013, 52, 2963-2967.

The workshop is generously supported by:

Ministry of Science, Education and Sports of the Republic of Croatia

International Union of Crystallography

European Crystallographic Association

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