Name: Dr. Ann Carolin Dumke
Diploma / M.Sc degree: Westfälische Wilhelms-Universität Münster, Germany
(January 2008)

PhD Project: N-Heterocyclic Carbenes - Synthesis and Coordination Chemistry


Homepage: http://www.uni-muenster.de/Chemie.ac/hahn/actual/dumke.html

Abstract of Research Project

One of the oldest methods to synthesize carbene complexes is through nucleophilic attack at the carbon atom of coordinated isocyanides. If the isocyanide contains the nucleophile itself, an intramolecular attack is possible, resulting in a cyclic carbene. Protic nucleophiles, like amines, have been shown to be suitable in this reaction, however β-aminophenyl- and β-aminoethylisocyanides are not stable in their free states. These compounds cyclize immediately to form imidazolin and benzimidazole, respectively. As a result, synthons are required. Suitable examples include azido and nitro groups.[1] After coordination to a metal center, reduction of the protective group is possible and, consequently, the amino group is formed. Still, these molecules are very reactive and form the corresponding carbene complexes. [2] The aim of our group is to achieve stabilization of these open amino-functionalized isocyanide complexes by variation of the metal-complex fragments. Electron-rich fragments are expected to avoid nucleophilic attack by increasing the electron density at the isocyanide carbon atom. [3,4]

If it is possible to control the ring closure reaction by variation of the metal-complex fragments, it should be also possible to switch between isocyanide and carbene ligands. This phenomenon may be achievable by ligand transfer or redox reactions at the metal center.

References:
[1] a) F. E. Hahn, V. Langenhahn, N. Meier, T. Lügger, W. P. Fehlhammer, Chem. Eur. J. 2003, 9, 207; b) F. E. Hahn, C. Garcia Plumed, M. Münder T. Lügger Chem. Eur. J. 2004, 10, 6285.
[2] C.-Y. Liu, D.-Y. Chen et al., Organometallics 1996, 15, 1055-1061.
[3] F. E. Hahn, L. Imhof, Organometallics 1997, 16, 763.
[4] F. E. Hahn, M. Tamm, Organometallics 1995, 14, 2597.



Publications

A. C. Dumke, T. Pape, J. Kösters, K.-O. Feldmann, C. Schulte to Brinke, F. E. Hahn
Metal-Template Controlled Stabilization of β-Functionalized Isocyanides
Organometallics 32 (2013), 289-299.


Ann Carolin Dumke
eMail: Ann Carolin Dumke